Arguments that have a default value but don't accept ()

[michaelhkay]

The following functions define an argument that has a default value, but don't allow () to be supplied explicitly:

lang
id
element-with-id
idref
parse-html

As determined by running the following query against the function catalog:

//*:arg[@default and not(ends-with(@type,'?') or ends-with(@type, '*'))]/(ancestor::*:function/(@prefix||':'||@name))

There are others which this query doesn't pick up, mainly where the defaultable argument is a function, including:

array:build map:build array:get map:get fn:highest fn:lowest