Obtain placeholder to insert it in another snippets

Good morning,
I would like to recover the placeholder [+wf.docid +] to insert it in other one snippets.
I tried with getPlaceholder: $docid=$modx-> getPlaceholder ("Wf.docid");
but it does not work.
Somebody have a solution?

Thank you and sorry for my poor english.

Arezius

I think [+id+] a placeholder or [*id*] the TV should work for you anywhere within MODx.