& (Ampersand)Wildcard port specifier.
only looks in port 1 for 'FOO' (except in the HP49/50 where it also looks in main memory if 'FOO' is not found in port 1).
looks for 'FOO' in port memory, then in the current directory, its parent directory, and so on all the way . Unfortunately, if 'FOO' is found, it is simply recalled with no indication given regarding where it was found.
HP49/50: These models start their search in port 0 and work upwards, unlike the HP48 which starts at the highest existing port and works downwards.
The only (?) commands that work with the wildcard port specifier are RCL, EVAL, PRVAR, and RESTORE.
Warning: STO ignores the wildcard port specifier.
completely ignores the :&:, and stores 153 into 'FOO' in main memory.
Contrary to the HP50g AUR, PURGE also ignores the wildcard port specifier.
always purges FOO from main memory, never from a port.