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http://www.w3.org/TR/html5/tabular-data.html#dom-tdth-colspan << The colSpan IDL attribute must reflect the content attribute of the same name. The value must be limited to only non-negative numbers _greater than zero_. >> In HTML4, "colspan" and "rowspan" attributes of TD/TH elements has been allowed to have zero value ("0"): http://www.w3.org/TR/html4/struct/tables.html#adef-colspan This is very useful when column or row number is unknown in advance. It's harmful to force web-editors to calculate column or row number manually while browser could easily do this automatically. There is a known rule in spec development: when there are two independent implementations of a specification, then the specification status is promoted to "recommendation" ("candidate" or "proposed"). But there ARE already two (well, 1.5) working independent implementations of zero colspan/rowspan: 1. Firefox (both zero colspan and rowspan are fully working) 2. and Opera (supports rowspan="0" and does not support colspan="0"). So, zero value of colspan/rowspan is very good candidate to keep in HTML spec and, moreover, to encourage rest browser vendors to implement this useful feature as soon as possible. There are no serious reasons to remove zero values of colspan/rowspan from the HTML specification. It's not something "unimplemented at all", it's already quite usably implemented and should be kept intact in the HTML spec. Thanks.
EDITOR'S RESPONSE: This is an Editor's Response to your comment. If you are satisfied with this response, please change the state of this bug to CLOSED. If you have additional information and would like the editor to reconsider, please reopen this bug. If you would like to escalate the issue to the full HTML Working Group, please add the TrackerRequest keyword to this bug, and suggest title and text for the tracker issue; or you may create a tracker issue yourself, if you are able to do so. For more details, see this document: http://dev.w3.org/html5/decision-policy/decision-policy.html Status: Rejected Change Description: no spec change Rationale: rowspan is supported in the spec. colspan is not because only Gecko supports it and it can't be done incrementally.
I don't see why it is harmful that colspan="0" "can't be done incrementally". An inportant use case is a row that spans the whole table. Writing a routine that generates such a row is currently only possible if the number of columns is given as a parameter to the routine, which is wasteful.