If you mean in terms of prefix usage, the answer is nothing more than already described. I did consider extending this prefix set quite a few years ago but decided it was not useful. In cases where I think confusion is possible, I simply use the remainder of the name to disambiguate. As a last resort, in cases of extreme comlexity, I use comments to describe the complete structure.

The main point is that the following should be known to be correct syntax:

$rh_abc->{def}
$ra_ghi->[jkl]
$rc_mno->('pqr')
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from inspection of the variable name. Without the prefixes, inspection of the code where the data originated (often in a separate module) is required.