Print files in FTP (RFC0448)
Original Publication Date: 1973-Feb-01
Included in the Prior Art Database: 2019-Feb-12
Internet Society Requests For Comment (RFCs)
NETWORK WORKING GROUP R.T. Braden REQUEST FOR COMMENT NO. 448 UCLA/CCN NIC #13299 February 27, 1973 UPDATES: RFC 354, 385, 454
PRINT FILES IN FTP
Many of those who contributed to the definition of the FTP and RJE protocols have expressed varying degrees of uncertainty or unhappiness with the "print file" type in FTP. This RFC is intended to review the problem of print files in preparation for the forthcoming FTP meeting. Originally drafted on the basis of RFC 385, this RFC has been updated to reflect the terminology of the latest FTP document 454. (Changing the terminology doesn’t solve the problem!)
It turns out that the Network RJE protocol as presently defined (see NIC 12112) seems to force a particular interpretation of print files in FTP and in fact, this interpretation is probably different from the one assumed by most FTP implementors.
VERTICAL FORMAT CONTROL -----------------------
What is a print file? Presumably it is a file which is intended to be sent (eventually) to a printer process to create a hard copy. Many operating systems (particularly those which are batch-processing oriented) allow the programmer to include control codes within a file to be printed, to control the vertical format of the printed page--for example, single/double line spacing, overprinting, and page ejection. A "print file" is one which includes such vertical format control ("VFC") information. There are three common ways for printer processes to determine VFC:
CASE N: Non-Print File -------------- The file contains no VFC information. The printer process applies a standard format (e.g., single space, standard vertical margins) if the file is printed.
CASE T: Print File with ASCII Format Effectors -------------------------------------- The file is "Telnet-like", containing the ASCII controls CR, LF, and FF to provide VFC.
Braden [Page 1]
RFC 448 PRINT FILES IN FTP February 1973
CASE A: Print File with ASA (Fortran) VFC --------------------------------- The first character of each record is a VFC code; see RFC 454 for the codes.
Assuming there are to be print files in FTP, these _three_ cases need to be considered. These three cases are explicitly included within the RJE protocol as "transmission" modes; we have borrowed the RJE labels N,T, and A from NIC #12112. The current FTP (RFC 454) seems to provide only _two_ cases: _unformatted_ and _print_file_. It is unclear from RFC 454 how these two FTP formats are related to the three VFC cases. For example, it is unclear whether the FTP format is meant to be a property of the file as transferred over the Network or of the file as stored by the server.
As I understand it, the Tenex system supports only case T. The distinction between Case N and Case T is not always clear, however. If a Tenex file which contains only the CR LF combination of format effectors is printed, it may be considered Case N where CR LF delimits a logical record, and where the standard format is to begin printing e...