There are links to function definitions missing from a number of tables in the 2nd edition PER of F&O.  The first edition of F&O doesn't have this same problem.  I suspect these are likely build-time problems:

In section 6.2, in the first table, links are missing for the references to op:numeric-integer-divide, op:numeric-unary-plus and op:numeric-unary-minus.

In section 6.3, a link to op:numeric-greater-than is missing from the table.

In section 6.4, a link to fn:round-half-to-even is missing from the table.

In section 10.4, links to op:yearMonthDuration-less-than, op:yearMonthDuration-greater-than, op:dayTimeDuration-less-than, op:dayTimeDuration-greater-than, op:dateTime-less-than and op:dateTime-greater-than are missing from the table.

In section 10.5, links to most of the functions referenced from the table are missing.

In section 10.6, links are missing for all of the arithmetic operators on durations referenced from the table.

In section 10.7, links are missing for all of the functions referenced from the table.

In section 10.8, links are missing for most of the functions references from the table.

In section 11.2, links to fn:local-name-from-QName, fn:namespace-uri-from-QName and fn:namespace-uri-for-prefix are missing from the table.

In section 12.1, a link for op:base64Binary-equal is missing from the table.

In section 15.5, there's no entry for the new fn:element-with-id function in the table.