How to Capture optional fields?

[JohnnyTsunami]

rex command im using:  (?:\w+\s\:\s)(?<command>[^\;]+)?\;\s(?<Datainput>[^\s]+)\s\;\s(?<Extra>[^\s]+)

Data

1) command : TTY-unknown ; data ; ... ;
2) command : Random blurb ; TTY-unknown ; data ; ... ;
3) command : Some other blurb ; TTY-unknown ; data ; ... ;
4) command : TTY-unknown ; data ; ... ;
5) command : TTY-unknown ; data ; ... ;

When I rex this data, what i get is:

	command	TTY	datainput
1	unknown	data	...
2	Random blurb	unknown	data
3	Some other blurb	unknown	data
4	unknown	data	...
5	unknown	data	...

What I want to get is data that doesn't skip the data in 2 and 3, so it would look like this.  How do I accomplish this?

	command	TTY	datainput
1		unknown	data
2	Random blurb	unknown	data
3	Some other blurb	unknown	data
4		unknown	data
5		unknown	data

[richgalloway]

IME, when fields are optional it is much simpler to use multiple rex commands - one for each optional field, plus one or more others for the static fields.