rfc1942.txt

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   COLGROUP elements can be used with the following attributes:

   ID, CLASS, LANG and DIR
       See earlier description of common attributes.

   SPAN
       A positive integer value that specifies a default for how many
       columns are in this group. This attribute should be ignored if
       the COLGROUP element contains one or more COL elements. It
       provides a convenient way of grouping columns without the need
       to supply COL elements.

   WIDTH
       Specifies a default width for each of the grouped columns, see
       standard units. In addition, the "*" suffix denotes relative
       widths, e.g.

            width=64        width in screen pixels
            width=0.5*      a relative width of 0.5

       Relative widths act as constraints on the relative widths of
       different columns. If a COLGROUP element specifies a relative
       width of zero, all of the columns in the group should be set to
       their minimum widths, unless they are associated with a COL
       element with an overriding WIDTH attribute. When widths are



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RFC 1942                      HTML Tables                       May 1996


       given in absolute units, the user agent can use these to
       constrain the width of the table. The "*" suffix is used to
       simplify importing tables from the CALS representation.

   ALIGN, CHAR, CHAROFF and VALIGN
       Specify values for horizontal and vertical alignment within
       table cells. See inheritance order of alignment properties.

The COL Element

   <!ELEMENT col - O EMPTY>

   <!ATTLIST col                      -- column groups and --
                                      -- properties --
           %attrs;                    -- id, lang, dir and class --
           span    NUMBER   1         -- number of columns spanned --
                                      -- by group --
           width   CDATA    #IMPLIED  -- column width specification --
           %cell.halign;              -- horizontal alignment in --
                                      -- cells --
           %cell.valign;              -- vertical alignment in cells --
           >

   This optional element is used to specify column based defaults for
   table properties. It is an empty element, and as such has no
   content, and shouldn't be given an end tag. Several COL elements may
   be given in succession. COL attributes override those of the parent
   COLGROUP element.

   ID, CLASS, LANG and DIR
       See earlier description of common attributes.

   SPAN
       A positive integer value that specifies how many columns this
       element applies to, defaulting to one. In the absence of SPAN
       attributes the first COL element applies to the first column,
       the second COL element to the second column and so on. If the
       second COL element had SPAN=2, it would apply to the second and
       third column. The next COL element would then apply to the
       fourth column and so on. SPAN=0 has a special significance and
       implies that the COL element spans all columns from the current
       column up to and including the last column. Note that a COL SPAN
       does not define a group. It is merely a way to share attribute
       definitions.







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RFC 1942                      HTML Tables                       May 1996


   WIDTH
       Specifies the width of the columns, see standard units. If the
       element spans several columns then the WIDTH attribute specifies
       the width for each of the individual columns - not the width of
       the span. In addition, the "*" suffix denotes relative widths,

       e.g.

            width=64        width in screen pixels
            width=0.5*      a relative width of 0.5

       Relative widths act as constraints on the relative widths of
       different columns. If a COL element specifies a relative width
       of zero, the column should always be set to its minimum width.
       When widths are given in absolute units, the user agent can use
       these to constrain the width of the table. The "*" suffix is
       used to simplify importing tables from the CALS representation.

   ALIGN, CHAR, CHAROFF and VALIGN
       Specify values for horizontal and vertical alignment within
       table cells. See inheritance order of alignment properties.

Table Head, Foot and Body Elements

   <!ELEMENT thead - O tr+>
   <!ELEMENT tfoot - O tr+>
   <!ELEMENT tbody O O tr+>

   <!ATTLIST (thead|tbody|tfoot)      -- table section --
           %attrs;                    -- id, lang, dir and class --
           %cell.halign;              -- horizontal alignment in --
                                      -- cells --
           %cell.valign;              -- vertical alignment in cells --
           >

   Tables may be divided up into head and body sections. The THEAD and
   TFOOT elements are optional, but one or more TBODY elements are
   always required. If the table only consists of a TBODY section, the
   TBODY start and end tags may be omitted, as the parser can infer
   them. If a THEAD element is present, the THEAD start tag is
   required, but the end tag can be omitted, provided a TFOOT or TBODY
   start tag follows. The same applies to TFOOT.

   Note: This definition provides compatibility with tables created
   for the older model, as well as allowing the end tags for THEAD,
   TFOOT and TBODY to be omitted.





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   The THEAD, TFOOT and TBODY elements provide a convenient means for
   controlling rendering. If the table has a large number of rows in
   the body, user agents may choose to use a scrolling region for the
   table body sections. When rendering to a paged device, tables will
   often have to be broken across page boundaries. The THEAD, TFOOT and
   TBODY elements allow the user agent to repeat the table foot at the
   bottom of the current page, and then the table head at the top of
   the new page before continuing on with the table body.

   TFOOT is placed before the TBODY in the markup sequence, so that
   browsers can render the foot before receiving all of the table data.
   This is useful when very long tables are rendered with scrolling
   body sections, or for paged output, involving breaking the table
   over many pages.

   Each THEAD, TFOOT and TBODY element must contain one or more TR
   elements.

   ID, CLASS, LANG and DIR
       See earlier description of common attributes.

   ALIGN, CHAR, CHAROFF and VALIGN
       Specify values for horizontal and vertical alignment within
       table cells. See inheritance order of alignment properties.

Table Row (TR) elements

   <!ELEMENT tr - O (th|td)+>

   <!ATTLIST tr                       -- table row --
           %attrs;                    -- id, lang, dir and class --
           %cell.halign;              -- horizontal alignment in --
                                      -- cells --
           %cell.valign;              -- vertical alignment in cells --
           >

   The TR or table row element acts as a container for a row of table
   cells. The end tag may be omitted.

   ID, CLASS, LANG and DIR
       See earlier description of common attributes.

   ALIGN, CHAR, CHAROFF and VALIGN
       Specify values for horizontal and vertical alignment within
       table cells. See inheritance order of alignment properties.






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Table Cells: TH and TD

   <!ELEMENT (th|td) - O %body.content>

   <!ATTLIST (th|td)                  -- header or data cell --
           %attrs;                    -- id, lang, dir and class --
           axis    CDATA    #IMPLIED  -- defaults to cell content --
           axes    CDATA    #IMPLIED  -- list of axis names --
           nowrap (nowrap)  #IMPLIED  -- suppress word wrap --
           rowspan NUMBER   1         -- number of rows spanned by --
                                      -- cell --
           colspan NUMBER   1         -- number of cols spanned by --
                                      -- cell --
           %cell.halign;              -- horizontal alignment in --
                                      -- cells --
           %cell.valign;              -- vertical alignment in cells --
           >

   TH elements are used to represent header cells, while TD elements
   are used to represent data cells. This allows user agents to render
   header and data cells distinctly, even in the absence of style
   sheets.

   Cells can span multiple rows and columns, and may be empty. Cells
   spanning rows contribute to the column count on each of the spanned
   rows, but only appear in the markup once (in the first row spanned).
   The row count is determined by the number of TR elements. Any rows
   implied by cells spanning rows beyond this should be ignored.

   If the column count for the table is greater than the number of
   cells for a given row (after including cells for spanned rows), the
   missing cells are treated as occurring on the right hand side of the
   table and rendered as empty cells. If the language context indicates
   a right to left writing order, then the missing cells should be
   placed on the left hand side.

   It is possible to create tables with overlapping cells, for
   instance:

       <table border>
       <tr><td rowspan=2>1<td>2<td>3
       <tr><td rowspan=2>4
       <tr><td colspan=2>5<td>6
       </table>







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   which might look something like:

       /-----------\
       | 1 | 2 | 3 |
       |   |-------|
       |   | 4 |   |
       |---|...|---|
       | 5 :   | 6 |
       \-----------/

   In this example, the cells labelled 4 and 5 overlap. In such cases,
   the rendering is implementation dependent.

   The AXIS and AXES attributes for cells provide a means for defining
   concise labels for cells. When rendering to speech, these attributes
   may be used to provide abbreviated names for the headers relevant to
   each cell. Another application is when you want to be able to later
   process table contents to enter them into a database. These
   attributes are then used to give database field names. The table's
   class attribute should be used to let the software recognize which
   tables can be treated in this way.

   ID, CLASS, LANG and DIR
       See earlier description of common attributes.

   AXIS
       This defines an abbreviated name for a header cell, e.g. which
       can be used when rendering to speech. It defaults to the cell's
       content.

   AXES
       This is a comma separated list of axis names which together
       identify the row and column headers that pertain to this cell.
       It is used for example when rendering to speech to identify the
       cell's position in the table. If missing the user agent can try
       to follow up columns and left along rows (right for some
       languages) to find the corresponding header cells.

   NOWRAP, e.g. <TD NOWRAP>
       The presence of this attribute disables automatic wrapping of
       text lines for this cell. If used uncautiously, it may result in
       excessively wide cells. This attribute is defined for backwards
       compatibility with deployed user agents. Greater control is
       possible with associated style sheet languages (for example for
       control over overflow handling).