The documentation says:
[...] a regular expression [...] can be used everywhere by referring to its name, prefixed with @[...]

But that seems not to be the case (see: ZBX-2112)

On precondition that the support 'everywhere' gets added in NMR (as it appears to be for ZBX-2112) please update the documentation to reflect the real case (at least for release 2.0.6).