Here is what the UL White Book has to say about Temp Light Strings.
TEMPORARY LIGHTING STRINGS
This listing covers temporary lighting strings which are rated 20 amps,125 volts, intended for use indoors and outdoors to provide temporary illumination in accordance with Article 527 of the National Electrical Code.
Temporary lighting strings consist of a factory assembly of flexible cord, cable or insulated open conductors incorporating a series of Edison base lampholders provided with lamp guards. The flexible cord may be terminated at one end with an attachment plug, for connection to the source of
supply, and with a cord connector at the opposite end. If an attachment plug is not provided, the temporary lighting string is provided with instructions for proper connection to the source of supply.
I was just working with some of these and the UL tag that said TEMPORARY LIGHTING STRING was on the cable itself, make sure the contractor does not rip these off before you see them.
Good Luck, Bob