SOURCE_ID_CFA, FETCH_CFA, SWAP_CFA, # Store current source on stack
SOURCE_ID_CFA, STORE_CFA, # Mark this as the current source
SOURCE_ID_CFA, FETCH_CFA, QUERY_FILE_CFA, # Read line from file
SOURCE_ID_CFA, FETCH_CFA, SWAP_CFA, # Store current source on stack
SOURCE_ID_CFA, STORE_CFA, # Mark this as the current source
SOURCE_ID_CFA, FETCH_CFA, QUERY_FILE_CFA, # Read line from file