List Structures in a Prefix (&)

O(\,"P"),""^SUB,DO{+&[SUB]^SUB SUB^/SLASH[SUB]}

/[SLASH,.ERR] = .ERR
/[SLASH,PM] = PM
/[SLASH,TF] = TF
/[SLASH,ZADT] = ZADT

Or just type: L / if slash is your prefix at the front end.