The are a number of limits which conspire to produce a maximum usable landing weight on any given occasion ...
(a) Type Certificate limiting weight .. often a structural limit
(b) WAT limit to provide a very modest climb capability in both the approach and landing missed approach cases
(c) runway limiting weight to give you a reasonable chance of not running off the end of the runway
(d) some people also have a look at the obstacle situation for a missed approach which can further complicate the matter.
After all these matters have been considered, it is normal to produce some data for pilot use, typically tabulations of OAT against wind component, with the most limiting of the various limiting weights recorded.
The resulting cockpit data is often given the term of regulated landing weight ... as good a name as any.