How does a travel document work?

[orbital]

As I understand when a USC is applying for a spouse's green card he can apply for her travel document and work permit at no additional cost. So, how exactly does a work permit work? Can she travel with it as she has a green card?

 

[Triple Citizen]

The Advance Parole dociment allows an AOS applicant to re-enter the US after international travel without abandoning the AOS application. It serves no purpose once the GC is approved.

So, how exactly does a work permit work? Can she travel with it as she has a green card?

 

[alimar]

As I understand when a USC is applying for a spouse's green card he can apply for her travel document and work permit at no additional cost. So, how exactly does a work permit work? Can she travel with it as she has a green card?

As the name says it is a work permit only, of course you can not travel with it.