TRWOV is a non-immigrant classification which stands for TRANSIT WITHOUT VISA -now TWOV- (not eligible to work) usually passing through the United States to another final destination country...
https://www.uscis.gov/tools/glossary/transit-without-visa-twov
Transit Without Visa (TWOV)
A transit alien traveling without a nonimmigrant visa under section 233 of the INA. An alien admitted under agreements with a transportation line, which guarantees his immediate and continuous passage to a foreign destination.
See also “Transit Alien”