Max length of an HTML attribute value

Question

How would I know what the maximum length of an element\'s attribute value is?

e.g.

What\'s

Answer 1

According to the SGML Declaration of HTML 4, the limit could be 65536 characters:

ATTSPLEN 65536   -- These are the largest values --
LITLEN   65536   -- permitted in the declaration --
NAMELEN  65536   -- Avoid fixed limits in actual --
PILEN    65536   -- implementations of HTML UA's --

The LITLEN limits the number of characters which can appear in a single attribute value literal and the ATTSPLEN limits the sum of all lengths of all attribute value specifications which appear in a tag.

Apparently, the limits used to be much lower in HTML 2, and people were complaining back then in 1995.