The text in section 10.4.4 xsl:evaluate as an optional feature mentions that xsl:evaluate can be either statically or dynamically disabled.

I have no clue how it could ever be dynamically disabled, but I guess that rule is there for a reason.

I raise this bug, however, because we don't specify the "should" in the final paragraph as implementation-defined. I think it should be (implementation-dependent doesn't seem to make sense here).

I propose to add the line:

"If a processor supports the dynamic evaluation features, it is implementation-defined how a processor allows users to turn off dynamic evaluation and it is implementation-defined whether this this is static or dynamic."