In my long document I, sadly, have to use several accents to denote different kinds of symbols. Currently, I use primes ($x'$), hat, tilde, and overline. In addition I use two colored symbols (red colored prime and blue $\prescript\ulcorner$), as I need further distinguishment.

Now I'd like to have no colors in my document, while I still have at least six different ways to differentiate certain symbols.

Which alternatives could I use that are easy to recognize and 'stand out', while they are different to prime/hat/tilde/overline?

EDIT: The reader should be able to see the kind of accent used even if the symbol in question is in a sub-script (possibly even a sub-sub-script).

In my long document I, sadly, have to use several accents to denote different kinds of symbols. Currently, I use primes ($x'$), hat, tilde, and overline. In addition I use two colored symbols (red colored tilde and blue $\prescript\ulcorner$), as I need further distinguishment.

Now I'd like to have no colors in my document, while I still have at least six different ways to differentiate certain symbols.

Which alternatives could I use that are easy to recognize and 'stand out', while they are different to prime/hat/tilde/overline?

EDIT: The reader should be able to see the kind of accent used even if the symbol in question is in a sub-script (possibly even a sub-sub-script).