In 4.2 "Module Declaration"...

"[Definition: a variable value (or the context item) depends on another variable value (or the context item) if, during the evaluation of the initializing expression of the former, the latter is accessed through the module context.]"

 -- s/ a / A /

 -- Shouldn't the words "depends on" be in bold?

"In the following example, the variable value $a depend onthe variable value $b ..."

 -- s/onthe/on the/

 -- s/depend on/depends on/

 -- $a is not a variable value, it's (roughly) the name of a variable.
    So s/the variable value $a/the value of variable $a/
    Ditto $b.

"This graph may not contain cycles ..."

 -- s/may not/must not/

Lastly, this stuff doesn't belong here. Section 4.2 is about module declarations, which only occur in library modules, but the 'depends on'
relation and error XQDY0054 are just as applicable to main modules.
Move it to 4.16 "Variable Declaration"?