Rem statements are not executed, but still may be branched to, for example from a goto statement. Execution continues with the first executable statement after the rem statement.
There may be no remarks on a data statement line since the rem or single quote introducing the remark would be interpreted as part of the data statement.
Rem statements are required when using the $include metacommand.
from The Basmark QuickBASIC Programmer’s Manual by Lawrence Leinweber