HTML(3)                                                   HTML(3)

     NAME
          parsehtml, printitems, validitems, freeitems, freedocinfo,
          dimenkind, dimenspec, targetid, targetname, fromStr, toStr -
          HTML parser

     SYNOPSIS
          #include <u.h>
          #include <libc.h>
          #include <html.h>

          Item*  parsehtml(uchar* data, int datalen, Rune* src, int mtype,
                 int chset, Docinfo** pdi)

          void   printitems(Item* items, char* msg)

          int    validitems(Item* items)

          void   freeitems(Item* items)

          void   freedocinfo(Docinfo* d)

          int    dimenkind(Dimen d)

          int    dimenspec(Dimen d)

          int    targetid(Rune* s)

          Rune*  targetname(int targid)

          uchar* fromStr(Rune* buf, int n, int chset)

          Rune*  toStr(uchar* buf, int n, int chset)

     DESCRIPTION
          This library implements a parser for HTML 4.0 documents.
          The parsed HTML is converted into an intermediate represen-
          tation that describes how the formatted HTML should be laid
          out.

          Parsehtml parses an entire HTML document contained in the
          buffer data and having length datalen. The URL of the docu-
          ment should be passed in as src. Mtype is the media type of
          the document, which should be either TextHtml or TextPlain.
          The character set of the document is described in chset,
          which can be one of US_Ascii, ISO_8859_1, UTF_8 or Unicode.
          The return value is a linked list of Item structures,
          described in detail below.  As a side effect, *pdi is set to
          point to a newly created Docinfo structure, containing
          information pertaining to the entire document.

     HTML(3)                                                   HTML(3)

          The library expects two allocation routines to be provided
          by the caller, emalloc and erealloc.  These routines are
          analogous to the standard malloc and realloc routines,
          except that they should not return if the memory allocation
          fails.  In addition, emalloc is required to zero the memory.

          For debugging purposes, printitems may be called to display
          the contents of an item list; individual items may be
          printed using the %I print verb, installed on the first call
          to parsehtml. validitems traverses the item list, checking
          that all of the pointers are valid.  It returns 1 is every-
          thing is ok, and 0 if an error was found.  Normally, one
          would not call these routines directly.  Instead, one sets
          the global variable dbgbuild and the library calls them
          automatically.  One can also set warn, to cause the library
          to print a warning whenever it finds a problem with the
          input document, and dbglex, to print debugging information
          in the lexer.

          When an item list is finished with, it should be freed with
          freeitems. Then, freedocinfo should be called on the pointer
          returned in *pdi.

          Dimenkind and dimenspec are provided to interpret the Dimen
          type, as described in the section Dimension Specifications.

          Frame target names are mapped to integer ids via a global,
          permanent mapping.  To find the value for a given name, call
          targetid, which allocates a new id if the name hasn't been
          seen before.  The name of a given, known id may be retrieved
          using targetname. The library predefines FTtop, FTself,
          FTparent and FTblank.

          The library handles all text as Unicode strings (type
          Rune*).  Character set conversion is provided by fromStr and
          toStr. FromStr takes n Unicode characters from buf and con-
          verts them to the character set described by chset. ToStr
          takes n bytes from buf, interpretted as belonging to charac-
          ter set chset, and converts them to a Unicode string.  Both
          routines null-terminate the result, and use emalloc to allo-
          cate space for it.

        Items
          The return value of parsehtml is a linked list of variant
          structures, with the generic portion described by the fol-
          lowing definition:

          typedef struct Item Item;
          struct Item
          {
                Item*    next;
                int      width;

     HTML(3)                                                   HTML(3)

                int      height;
                int      ascent;
                int      anchorid;
                int      state;
                Genattr* genattr;
                int      tag;
          };

          The field next points to the successor in the linked list of
          items, while width, height, and ascent are intended for use
          by the caller as part of the layout process.  Anchorid, if
          non-zero, gives the integer id assigned by the parser to the
          anchor that this item is in (see section Anchors). State is
          a collection of flags and values described as follows:

          enum
          {
                IFbrk =         0x80000000,
                IFbrksp =       0x40000000,
                IFnobrk =       0x20000000,
                IFcleft =       0x10000000,
                IFcright =      0x08000000,
                IFwrap =        0x04000000,
                IFhang =        0x02000000,
                IFrjust =       0x01000000,
                IFcjust =       0x00800000,
                IFsmap =        0x00400000,
                IFindentshift = 8,
                IFindentmask =  (255<<IFindentshift),
                IFhangmask =    255
          };

          IFbrk is set if a break is to be forced before placing this
          item.  IFbrksp is set if a 1 line space should be added to
          the break (in which case IFbrk is also set).  IFnobrk is set
          if a break is not permitted before the item.  IFcleft is set
          if left floats should be cleared (that is, if the list of
          pending left floats should be placed) before this item is
          placed, and IFcright is set for right floats.  In both
          cases, IFbrk is also set.  IFwrap is set if the line con-
          taining this item is allowed to wrap.  IFhang is set if this
          item hangs into the left indent.  IFrjust is set if the line
          containing this item should be right justified, and IFcjust
          is set for center justified lines.  IFsmap is used to indi-
          cate that an image is a server-side map.  The low 8 bits,
          represented by IFhangmask, indicate the current hang into
          left indent, in tenths of a tabstop.  The next 8 bits, rep-
          resented by IFindentmask and IFindentshift, indicate the
          current indent in tab stops.

          The field genattr is an optional pointer to an auxiliary
          structure, described in the section Generic Attributes.

     HTML(3)                                                   HTML(3)

          Finally, tag describes which variant type this item has.  It
          can have one of the values Itexttag, Iruletag, Iimagetag,
          Iformfieldtag, Itabletag, Ifloattag or Ispacertag.  For each
          of these values, there is an additional structure defined,
          which includes Item as an unnamed initial substructure, and
          then defines additional fields.

          Items of type Itexttag represent a piece of text, using the
          following structure:

          struct Itext
          {
                Item;
                Rune* s;
                int   fnt;
                int   fg;
                uchar voff;
                uchar ul;
          };

          Here s is a null-terminated Unicode string of the actual
          characters making up this text item, fnt is the font number
          (described in the section Font Numbers), and fg is the RGB
          encoded color for the text.  Voff measures the vertical off-
          set from the baseline; subtract Voffbias to get the actual
          value (negative values represent a displacement down the
          page).  The field ul is the underline style: ULnone if no
          underline, ULunder for conventional underline, and ULmid for
          strike-through.

          Items of type Iruletag represent a horizontal rule, as fol-
          lows:

          struct Irule
          {
                Item;
                uchar align;
                uchar noshade;
                int   size;
                Dimen wspec;
          };

          Here align is the alignment specification (described in the
          corresponding section), noshade is set if the rule should
          not be shaded, size is the height of the rule (as set by the
          size attribute), and wspec is the desired width (see section
          Dimension Specifications).

          Items of type Iimagetag describe embedded images, for which
          the following structure is defined:

          struct Iimage

     HTML(3)                                                   HTML(3)

          {
                Item;
                Rune*   imsrc;
                int     imwidth;
                int     imheight;
                Rune*   altrep;
                Map*    map;
                int     ctlid;
                uchar   align;
                uchar   hspace;
                uchar   vspace;
                uchar   border;
                Iimage* nextimage;
          };

          Here imsrc is the URL of the image source, imwidth and
          imheight, if non-zero, contain the specified width and
          height for the image, and altrep is the text to use as an
          alternative to the image, if the image is not displayed.
          Map, if set, points to a structure describing an associated
          client-side image map.  Ctlid is reserved for use by the
          application, for handling animated images.  Align encodes
          the alignment specification of the image.  Hspace contains
          the number of pixels to pad the image with on either side,
          and Vspace the padding above and below.  Border is the width
          of the border to draw around the image.  Nextimage points to
          the next image in the document (the head of this list is
          Docinfo.images).

          For items of type Iformfieldtag, the following structure is
          defined:

          struct Iformfield
          {
                Item;
                Formfield* formfield;
          };

          This adds a single field, formfield, which points to a
          structure describing a field in a form, described in section
          Forms.

          For items of type Itabletag, the following structure is
          defined:

          struct Itable
          {
                Item;
                Table* table;
          };

          Table points to a structure describing the table, described

     HTML(3)                                                   HTML(3)

          in the section Tables.

          For items of type Ifloattag, the following structure is
          defined:

          struct Ifloat
          {
                Item;
                Item*   item;
                int     x;
                int     y;
                uchar   side;
                uchar   infloats;
                Ifloat* nextfloat;
          };

          The item points to a single item (either a table or an
          image) that floats (the text of the document flows around
          it), and side indicates the margin that this float sticks
          to; it is either ALleft or ALright.  X and y are reserved
          for use by the caller; these are typically used for the
          coordinates of the top of the float.  Infloats is used by
          the caller to keep track of whether it has placed the float.
          Nextfloat is used by the caller to link together all of the
          floats that it has placed.

          For items of type Ispacertag, the following structure is
          defined:

          struct Ispacer
          {
                Item;
                int   spkind;
          };

          Spkind encodes the kind of spacer, and may be one of ISPnull
          (zero height and width), ISPvline (takes on height and
          ascent of the current font), ISPhspace (has the width of a
          space in the current font) and ISPgeneral (for all other
          purposes, such as between markers and lists).

        Generic Attributes
          The genattr field of an item, if non-nil, points to a struc-
          ture that holds the values of attributes not specific to any
          particular item type, as they occur on a wide variety of
          underlying HTML tags.  The structure is as follows:

          typedef struct Genattr Genattr;
          struct Genattr
          {
                Rune*   id;
                Rune*   class;

     HTML(3)                                                   HTML(3)

                Rune*   style;
                Rune*   title;
                SEvent* events;
          };

          Fields id, class, style and title, when non-nil, contain
          values of correspondingly named attributes of the HTML tag
          associated with this item.  Events is a linked list of
          events (with corresponding scripted actions) associated with
          the item:

          typedef struct SEvent SEvent;
          struct SEvent
          {
                SEvent* next;
                int     type;
                Rune*   script;
          };

          Here, next points to the next event in the list, type is one
          of SEonblur, SEonchange, SEonclick, SEondblclick, SEonfocus,
          SEonkeypress, SEonkeyup, SEonload, SEonmousedown,
          SEonmousemove, SEonmouseout, SEonmouseover, SEonmouseup,
          SEonreset, SEonselect, SEonsubmit or SEonunload, and script
          is the text of the associated script.

        Dimension Specifications
          Some structures include a dimension specification, used
          where a number can be followed by a % or a * to indicate
          percentage of total or relative weight.  This is encoded
          using the following structure:

          typedef struct Dimen Dimen;
          struct Dimen
          {
                int kindspec;
          };

          Separate kind and spec values are extracted using dimenkind
          and dimenspec. Dimenkind returns one of Dnone, Dpixels,
          Dpercent or Drelative.  Dnone means that no dimension was
          specified.  In all other cases, dimenspec should be called
          to find the absolute number of pixels, the percentage of
          total, or the relative weight.

        Background Specifications
          It is possible to set the background of the entire document,
          and also for some parts of the document (such as tables).
          This is encoded as follows:

          typedef struct Background Background;
          struct Background

     HTML(3)                                                   HTML(3)

          {
                Rune* image;
                int   color;
          };

          Image, if non-nil, is the URL of an image to use as the
          background.  If this is nil, color is used instead, as the
          RGB value for a solid fill color.

        Alignment Specifications
          Certain items have alignment specifiers taken from the fol-
          lowing enumerated type:

          enum
          {
                ALnone = 0, ALleft, ALcenter, ALright, ALjustify,
                ALchar, ALtop, ALmiddle, ALbottom, ALbaseline
          };

          These values correspond to the various alignment types named
          in the HTML 4.0 standard.  If an item has an alignment of
          ALleft or ALright, the library automatically encapsulates it
          inside a float item.

          Tables, and the various rows, columns and cells within them,
          have a more complex alignment specification, composed of
          separate vertical and horizontal alignments:

          typedef struct Align Align;
          struct Align
          {
                uchar halign;
                uchar valign;
          };

          Halign can be one of ALnone, ALleft, ALcenter, ALright,
          ALjustify or ALchar.  Valign can be one of ALnone, ALmiddle,
          ALbottom, ALtop or ALbaseline.

        Font Numbers
          Text items have an associated font number (the fnt field),
          which is encoded as style*NumSize+size.  Here, style is one
          of FntR, FntI, FntB or FntT, for roman, italic, bold and
          typewriter font styles, respectively, and size is Tiny,
          Small, Normal, Large or Verylarge.  The total number of pos-
          sible font numbers is NumFnt, and the default font number is
          DefFnt (which is roman style, normal size).

        Document Info
          Global information about an HTML page is stored in the fol-
          lowing structure:

     HTML(3)                                                   HTML(3)

          typedef struct Docinfo Docinfo;
          struct Docinfo
          {
                // stuff from HTTP headers, doc head, and body tag
                Rune*       src;
                Rune*       base;
                Rune*       doctitle;
                Background  background;
                Iimage*     backgrounditem;
                int         text;
                int         link;
                int         vlink;
                int         alink;
                int         target;
                int         chset;
                int         mediatype;
                int         scripttype;
                int         hasscripts;
                Rune*       refresh;
                Kidinfo*    kidinfo;
                int         frameid;

                // info needed to respond to user actions
                Anchor*     anchors;
                DestAnchor* dests;
                Form*       forms;
                Table*      tables;
                Map*        maps;
                Iimage*     images;
          };

          Src gives the URL of the original source of the document,
          and base is the base URL.  Doctitle is the document's title,
          as set by a <title> element.  Background is as described in
          the section Background Specifications, and backgrounditem is
          set to be an image item for the document's background image
          (if given as a URL), or else nil.  Text gives the default
          foregound text color of the document, link the unvisited
          hyperlink color, vlink the visited hyperlink color, and
          alink the color for highlighting hyperlinks (all in 24-bit
          RGB format).  Target is the default target frame id.  Chset
          and mediatype are as for the chset and mtype parameters to
          parsehtml. Scripttype is the type of any scripts contained
          in the document, and is always TextJavascript.  Hasscripts
          is set if the document contains any scripts.  Scripting is
          currently unsupported.  Refresh is the contents of a <meta
          http-equiv=Refresh ...> tag, if any.  Kidinfo is set if this
          document is a frameset (see section Frames). Frameid is this
          document's frame id.

          Anchors is a list of hyperlinks contained in the document,
          and dests is a list of hyperlink destinations within the

     HTML(3)                                                   HTML(3)

          page (see the following section for details).  Forms, tables
          and maps are lists of the various forms, tables and client-
          side maps contained in the document, as described in subse-
          quent sections.  Images is a list of all the image items in
          the document.

        Anchors
          The library builds two lists for all of the <a> elements
          (anchors) in a document.  Each anchor is assigned a unique
          anchor id within the document.  For anchors which are hyper-
          links (the href attribute was supplied), the following
          structure is defined:

          typedef struct Anchor Anchor;
          struct Anchor
          {
                Anchor* next;
                int     index;
                Rune*   name;
                Rune*   href;
                int     target;
          };

          Next points to the next anchor in the list (the head of this
          list is Docinfo.anchors).  Index is the anchor id; each item
          within this hyperlink is tagged with this value in its
          anchorid field.  Name and href are the values of the corre-
          spondingly named attributes of the anchor (in particular,
          href is the URL to go to).  Target is the value of the tar-
          get attribute (if provided) converted to a frame id.

          Destinations within the document (anchors with the name
          attribute set) are held in the Docinfo.dests list, using the
          following structure:

          typedef struct DestAnchor DestAnchor;
          struct DestAnchor
          {
                DestAnchor* next;
                int         index;
                Rune*       name;
                Item*       item;
          };

          Next is the next element of the list, index is the anchor
          id, name is the value of the name attribute, and item is
          points to the item within the parsed document that should be
          considered to be the destination.

        Forms
          Any forms within a document are kept in a list, headed by
          Docinfo.forms.  The elements of this list are as follows:

     HTML(3)                                                   HTML(3)

          typedef struct Form Form;
          struct Form
          {
                Form*      next;
                int        formid;
                Rune*      name;
                Rune*      action;
                int        target;
                int        method;
                int        nfields;
                Formfield* fields;
          };

          Next points to the next form in the list.  Formid is a
          serial number for the form within the document.  Name is the
          value of the form's name or id attribute.  Action is the
          value of any action attribute.  Target is the value of the
          target attribute (if any) converted to a frame target id.
          Method is one of HGet or HPost.  Nfields is the number of
          fields in the form, and fields is a linked list of the
          actual fields.

          The individual fields in a form are described by the follow-
          ing structure:

          typedef struct Formfield Formfield;
          struct Formfield
          {
                Formfield* next;
                int        ftype;
                int        fieldid;
                Form*      form;
                Rune*      name;
                Rune*      value;
                int        size;
                int        maxlength;
                int        rows;
                int        cols;
                uchar      flags;
                Option*    options;
                Item*      image;
                int        ctlid;
                SEvent*    events;
          };

          Here, next points to the next field in the list.  Ftype is
          the type of the field, which can be one of Ftext, Fpassword,
          Fcheckbox, Fradio, Fsubmit, Fhidden, Fimage, Freset, Ffile,
          Fbutton, Fselect or Ftextarea.  Fieldid is a serial number
          for the field within the form.  Form points back to the form
          containing this field.  Name, value, size, maxlength, rows
          and cols each contain the values of corresponding attributes

     HTML(3)                                                   HTML(3)

          of the field, if present.  Flags contains per-field flags,
          of which FFchecked and FFmultiple are defined.  Image is
          only used for fields of type Fimage; it points to an image
          item containing the image to be displayed.  Ctlid is
          reserved for use by the caller, typically to store a unique
          id of an associated control used to implement the field.
          Events is the same as the corresponding field of the generic
          attributes associated with the item containing this field.
          Options is only used by fields of type Fselect; it consists
          of a list of possible options that may be selected for that
          field, using the following structure:

          typedef struct Option Option;
          struct Option
          {
                Option* next;
                int     selected;
                Rune*   value;
                Rune*   display;
          };

          Next points to the next element of the list.  Selected is
          set if this option is to be displayed initially.  Value is
          the value to send when the form is submitted if this option
          is selected.  Display is the string to display on the screen
          for this option.

        Tables
          The library builds a list of all the tables in the document,
          headed by Docinfo.tables.  Each element of this list has the
          following format:

          typedef struct Table Table;
          struct Table
          {
                Table*       next;
                int          tableid;
                Tablerow*    rows;
                int          nrow;
                Tablecol*    cols;
                int          ncol;
                Tablecell*   cells;
                int          ncell;
                Tablecell*** grid;
                Align        align;
                Dimen        width;
                int          border;
                int          cellspacing;
                int          cellpadding;
                Background   background;
                Item*        caption;
                uchar        caption_place;

     HTML(3)                                                   HTML(3)

                Lay*         caption_lay;
                int          totw;
                int          toth;
                int          caph;
                int          availw;
                Token*       tabletok;
                uchar        flags;
          };

          Next points to the next element in the list of tables.
          Tableid is a serial number for the table within the docu-
          ment.  Rows is an array of row specifications (described
          below) and nrow is the number of elements in this array.
          Similarly, cols is an array of column specifications, and
          ncol the size of this array.  Cells is a list of all cells
          within the table (structure described below) and ncell is
          the number of elements in this list.  Note that a cell may
          span multiple rows and/or columns, thus ncell may be smaller
          than nrow*ncol.  Grid is a two-dimensional array of cells
          within the table; the cell at row i and column j is
          Table.grid[i][j].  A cell that spans multiple rows and/or
          columns will be referenced by grid multiple times, however
          it will only occur once in cells.  Align gives the alignment
          specification for the entire table, and width gives the
          requested width as a dimension specification.  Border,
          cellspacing and cellpadding give the values of the corre-
          sponding attributes for the table, and background gives the
          requested background for the table.  Caption is a linked
          list of items to be displayed as the caption of the table,
          either above or below depending on whether caption_place is
          ALtop or ALbottom.  Most of the remaining fields are
          reserved for use by the caller, except tabletok, which is
          reserved for internal use.  The type Lay is not defined by
          the library; the caller can provide its own definition.

          The Tablecol structure is defined for use by the caller.
          The library ensures that the correct number of these is
          allocated, but leaves them blank.  The fields are as fol-
          lows:

          typedef struct Tablecol Tablecol;
          struct Tablecol
          {
                int   width;
                Align align;
                Point pos;
          };

          The rows in the table are specified as follows:

          typedef struct Tablerow Tablerow;
          struct Tablerow

     HTML(3)                                                   HTML(3)

          {
                Tablerow*  next;
                Tablecell* cells;
                int        height;
                int        ascent;
                Align      align;
                Background background;
                Point      pos;
                uchar      flags;
          };

          Next is only used during parsing; it should be ignored by
          the caller.  Cells provides a list of all the cells in a
          row, linked through their nextinrow fields (see below).
          Height, ascent and pos are reserved for use by the caller.
          Align is the alignment specification for the row, and
          background is the background to use, if specified.  Flags is
          used by the parser; ignore this field.

          The individual cells of the table are described as follows:

          typedef struct Tablecell Tablecell;
          struct Tablecell
          {
                Tablecell* next;
                Tablecell* nextinrow;
                int        cellid;
                Item*      content;
                Lay*       lay;
                int        rowspan;
                int        colspan;
                Align      align;
                uchar      flags;
                Dimen      wspec;
                int        hspec;
                Background background;
                int        minw;
                int        maxw;
                int        ascent;
                int        row;
                int        col;
                Point      pos;
          };

          Next is used to link together the list of all cells within a
          table (Table.cells), whereas nextinrow is used to link
          together all the cells within a single row (Tablerow.cells).
          Cellid provides a serial number for the cell within the
          table.  Content is a linked list of the items to be laid out
          within the cell.  Lay is reserved for the user to describe
          how these items have been laid out.  Rowspan and colspan are
          the number of rows and columns spanned by this cell,

     HTML(3)                                                   HTML(3)

          respectively.  Align is the alignment specification for the
          cell.  Flags is some combination of TFparsing, TFnowrap and
          TFisth or'd together.  Here TFparsing is used internally by
          the parser, and should be ignored.  TFnowrap means that the
          contents of the cell should not be wrapped if they don't fit
          the available width, rather, the table should be expanded if
          need be (this is set when the nowrap attribute is supplied).
          TFisth means that the cell was created by the <th> element
          (rather than the <td> element), indicating that it is a
          header cell rather than a data cell.  Wspec provides a sug-
          gested width as a dimension specification, and hspec pro-
          vides a suggested height in pixels.  Background gives a
          background specification for the individual cell.  Minw,
          maxw, ascent and pos are reserved for use by the caller dur-
          ing layout.  Row and col give the indices of the row and
          column of the top left-hand corner of the cell within the
          table grid.

        Client-side Maps
          The library builds a list of client-side maps, headed by
          Docinfo.maps, and having the following structure:

          typedef struct Map Map;
          struct Map
          {
                Map*  next;
                Rune* name;
                Area* areas;
          };

          Next points to the next element in the list, name is the
          name of the map (use to bind it to an image), and areas is a
          list of the areas within the image that comprise the map,
          using the following structure:

          typedef struct Area Area;
          struct Area
          {
                Area*  next;
                int    shape;
                Rune*  href;
                int    target;
                Dimen* coords;
                int    ncoords;
          };

          Next points to the next element in the map's list of areas.
          Shape describes the shape of the area, and is one of SHrect,
          SHcircle or SHpoly.  Href is the URL associated with this
          area in its role as a hypertext link, and target is the tar-
          get frame it should be loaded in.  Coords is an array of
          coordinates for the shape, and ncoords is the size of this

     HTML(3)                                                   HTML(3)

          array (number of elements).

        Frames
          If the Docinfo.kidinfo field is set, the document is a
          frameset.  In this case, it is typical for parsehtml to
          return nil, as a document which is a frameset should have no
          actual items that need to be laid out (such will appear only
          in subsidiary documents).  It is possible that items will be
          returned by a malformed document; the caller should check
          for this and free any such items.

          The Kidinfo structure itself reflects the fact that frame-
          sets can be nested within a document.  If is defined as fol-
          lows:

          typedef struct Kidinfo Kidinfo;
          struct Kidinfo
          {
                Kidinfo* next;
                int      isframeset;

                // fields for "frame"
                Rune*    src;
                Rune*    name;
                int      marginw;
                int      marginh;
                int      framebd;
                int      flags;

                // fields for "frameset"
                Dimen*   rows;
                int      nrows;
                Dimen*   cols;
                int      ncols;
                Kidinfo* kidinfos;
                Kidinfo* nextframeset;
          };

          Next is only used if this structure is part of a containing
          frameset; it points to the next element in the list of chil-
          dren of that frameset.  Isframeset is set when this struc-
          ture represents a frameset; if clear, it is an individual
          frame.

          Some fields are used only for framesets.  Rows is an array
          of dimension specifications for rows in the frameset, and
          nrows is the length of this array.  Cols is the correspond-
          ing array for columns, of length ncols.  Kidinfos points to
          a list of components contained within this frameset, each of
          which may be a frameset or a frame.  Nextframeset is only
          used during parsing, and should be ignored.

     HTML(3)                                                   HTML(3)

          The remaining fields are used if the structure describes a
          frame, not a frameset.  Src provides the URL for the docu-
          ment that should be initially loaded into this frame.  Note
          that this may be a relative URL, in which case it should be
          interpretted using the containing document's URL as the
          base.  Name gives the name of the frame, typically supplied
          via a name attribute in the HTML.  If no name was given, the
          library allocates one.  Marginw, marginh and framebd are the
          values of the marginwidth, marginheight and frameborder
          attributes, respectively.  Flags can contain some combina-
          tion of the following: FRnoresize (the frame had the nore-
          size attribute set, and the user should not be allowed to
          resize it), FRnoscroll (the frame should not have any scroll
          bars), FRhscroll (the frame should have a horizontal scroll
          bar), FRvscroll (the frame should have a vertical scroll
          bar), FRhscrollauto (the frame should be automatically given
          a horizontal scroll bar if its contents would not otherwise
          fit), and FRvscrollauto (the frame gets a vertical scrollbar
          only if required).

     SOURCE
          /src/libhtml

     SEE ALSO
          fmt(1)

          W3C World Wide Web Consortium, ``HTML 4.01 Specification''.

     BUGS
          The entire HTML document must be loaded into memory before
          any of it can be parsed.