A regular expression question

Hello All,

I have a question about regular expression. For example:

ECExpression: this.SERVICE_NAME & "-" & this.UNIT_NAME & “-” & this.SPECIFICATION & “-” & this.NUMBER

Regular expression: ^[?\w]*-[?\w]*-(?<SPECIFICATION>[?\w]*)-(?<NUMBER>.*)|(?<NUMBER>.*)

I don't understand the last part (?<NUMBER>.*)|(?<NUMBER>.*) The last part is NUMBER or NUMBER? Can anyone explain to me? Thanks a lot!