Hello monks!
I wanted to double-check something that I have noticed with you (maybe I am wrong, please bear with me). If I have a hash with keys that have special characters like $ or | or ., is this a problem? I am working with protein sequence data, that have IDs like the following: 
>tr|Q8PV56|Q8PV56_METMA PEP-CTERM sorting domain-containing protein OS
+=Methanosarcina mazei (strain ATCC BAA-159 / DSM 3647 / Goe1 / Go1 / 
+JCM 11833 / OCM 88) OX=192952 GN=MM_2118 PE=4 SV=1

[download]

Can all the above be stored as a hash key (length-wise I mean). Will there be any issue if e.g. I try to execute a command like if exists($hash{$key})
Thank you for your guidance!

In reply to Potential hash key ids limitations by Anonymous Monk

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.