> such variables are typically undocumented package variables,

FWIW: There is an old poor man's trick to make package vars readonly, by assigning refs of literals to globs. 

  DB<35> *RO=\5

  DB<36> p $RO
5
  DB<37> $RO=6
Modification of a read-only value attempted at (eval 51) ...

[download]

HTH! :)

Cheers Rolf
(addicted to the 𐍀𐌴𐍂𐌻 Programming Language :)
Wikisyntax for the Monastery

In reply to Re^3: constants in an RE by LanX
in thread constants in an RE by BernieC

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