Metadata expressions

[Mike Caceres]

If I have a document with the following metadata values:"protocol_name" : 
"Protocol 1234500 (USPA00012345) second version"
and I want to produce a new metadata field that looks like this:
"protocol_id" : "Protocol-1234500"
should the metadata expression look like this?
parameter name = protocol_id remove this parameter = false expression = 
Protocol-${protocol_name|string(\d+)|0}
Thank you!