Modes: a q s
EXTERNAL uses an external application to retrieve sequences. The ID is passed as an argument to the application, either replacing %s in the command string (if present) or as an additional arguement (if there is no %s). EXTERNAL expects the application to return the sequence on STDOUT.
DB mydb [ #required parameters method: app format: fasta app: "getfromdb mydb" #optional parameters type: P comment: "my own protein database with a custom retrieval program" ]