I took a quick look into Ralf Brown's Interrupt List and the material is far too vast to be easily understood.
Yes, it is not for the faint of heart.
Please consider providing a SSCCE with sample input if you need further help.
The answers so far are already very satisfying.
the Xs in your hex character class look wrong, I suppose they are only allowed at the beginning like xFF
No, some MEM and @ (CALL) references do use literal Xes instead of hexits. Such as if there's references to "MEM xxxxh:xxx0h - Multiprocessor Specification - FLOATING POINTER STRUCTURE" or "CALL xxxxh:xxxxh - Alternate Multiplex Interrupt Specification TSRs"
you should consider a match all clause like (?<unknown>.*) at the end of your branches, to catch errors or missing implementations (e.g a weird number where you expected a hex)

I don't understand this. I don't want to match anything if there's no hyperlink reference in a given line. (Actually in one case I do want to know nothing was matched but it's not a problem, I just do last MATCHLINK before and if the code afterwards is run after having entered a single "link" item, I know nothing was matched.)

Thanks!

In reply to Re^5: Reusing a complex regexp in multiple spots, escaping the regexp by ecm
in thread Reusing a complex regexp in multiple spots, escaping the regexp by ecm

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.