TH - Table Header Cell

The TH element defines a header cell in a table. TH elements are contained within a TR element (a table row), which may also contain TD elements for data cells. When a cell's contents act as both header information and table data, TD should be used.

The ROWSPAN and COLSPAN attributes of TH specify the number of rows and the number of columns, respectively, that are spanned by the cell. The default value is 1. The special value 0 indicates that the cell spans all rows or columns to the end of the table. The value 0 is ignored by most browsers, so authors may wish to calculate the exact number of rows or columns spanned and use that value.

The HEADERS attribute specifies the header cells that apply to the TH. The value is a space-separated list of the header cells' ID attribute values. The HEADERS attribute allows non-visual browsers to render the header information for a given cell.

The ABBR attribute gives an abbreviated version of the cell's content. This allows visual browsers to use the short form if space is limited, and non-visual browsers can give a cell's header information in an abbreviated form before rendering each cell.

The SCOPE attribute specifies the cells for which the TH element provides header information. SCOPE is a simpler alternative to using HEADERS if the arrangement of header cells is not complex. Possible values are as follows:

• row, when the TH provides header information for the rest of the row;
• col, when the TH provides header information for the rest of the column;
• rowgroup, when the TH gives header information for the rest of the row group (i.e., the remaining cells of the THEAD, TFOOT, or TBODY);
• colgroup, when the TH gives header information for the rest of the column group (i.e., the remaining cells of the COLGROUP).

The AXIS attribute provides a method of categorizing cells. The attribute's value is a comma-separated list of category names. See the HTML 4.0 Recommendation's section on categorizing cells for an application of AXIS.

In addition to the attributes common to most elements, TH takes a number of presentational attributes. Style sheets provide a more flexible way to suggest a presentation for table cells, but TH's presentational attributes are more widely supported by current browsers.

The ALIGN attribute specifies the horizontal alignment for the cell. Possible values are left, center, right, justify, and char. ALIGN=char, poorly supported among browsers, aligns a cell's contents on the character given in the CHAR attribute. The default value for the CHAR attribute is the decimal point of the current language--a period in English. The CHAROFF attribute specifies the offset to the first occurrence of the alignment character. The attribute's value is a number in pixels or a percentage of the cell's width; CHAROFF="50%" centers the alignment character horizontally in a cell.

The VALIGN attribute specifies the vertical position of a cell's contents. Possible values are:

• top, which positions data at the top of the cell;
• middle, the default value, which centers the cell data vertically;
• bottom, which positions data at the bottom of the cell;
• baseline, which specifies that the first line of each cell in the row with VALIGN=baseline should occur on a common baseline.

More Information

• TH in W3C HTML 4.0 Recommendation
• TH in W3C HTML 3.2 Recommendation
• TH in WDG HTML 3.2 Reference
• TH in Learning HTML 3.2 by Examples

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