[RFC 500] The Integration of Data Management Systems on a Computer Network.

[RFC 501] Un-Muddling "Free File Transfer".

[RFC 502]

• Never issued.

[RFC 503] Socket Number List.

• Obsoleted by:
  RFC 750, RFC 755, RFC 758, RFC 762, RFC 770, RFC 776, RFC 790, RFC 820.
• References:
  RFC 349, RFC 433.

[RFC 504] Workshop Announcement.

• Meeting notice.

[RFC 505] Two Solutions to a File Transfer Access Problem.

[RFC 506] An FTP Command-Naming Problem.

[RFC 507]

• Never issued.

[RFC 508] REAL-TIME DATA TRANSMISSION ON THE ARPANET.

[RFC 509] Traffic Statistics (April 1973).

• Updates:
  RFC 497, RFC 522.

[RFC 510] Request for Network Mailbox Addresses.

[RFC 511] Enterprise Phone Service to NIC From ARPANET Sites.

[RFC 512] MORE ON LOST MESSAGE DETECTION.

[RFC 513] COMMENTS ON THE NEW TELNET SPECIFICATIONS.

[RFC 514] NETWORK MAKE-WORK.

• Updates:
  RFC 459.

[RFC 515] Specifications for Datalanguage, Version 0/9.

[RFC 516] LOST MESSAGE DETECTION.

[RFC 517]

• Never issued.

[RFC 518] ARPANET ACCOUNTS.

[RFC 519] Resource Evaluation.

[RFC 520] A Proposed File Access Protocol Specification.

[RFC 521] Restricted Use of IMP DDT.

[RFC 522] Traffic Statistics.

• Updated by:
  RFC 538.
• Updates:
  RFC 509.

[RFC 523] SURVEY is in Operation Again.

[RFC 524] A Proposed Mail Protocol.

[RFC 525] MIT-MATHLAB MEETS UCSB-OLS: An Example of Resource Sharing.

[RFC 526] Technical Meeting Digital Image Processing Software Systems July 17-18, 1973 University of Southern California.

• Meeting notice.

[RFC 527] ARPAWOCKY.

• Humor.

[RFC 528] SOFTWARE CHECKSUMMING IN THE IMP AND NETWORK RELIABILITY.

[RFC 529] A Note on Protocol Synch Sequences.

• References:
  RFC 454, RFC 513.

[RFC 530] A Report on the SURVEY Project.

[RFC 531] Feast or famine? A Response to Two Recent RFC's About Network Information.

[RFC 532] The UCSD-CC Server-FTP Facility.

[RFC 533] MESSAGE-ID NUMBERS.

[RFC 534] Lost Message Detection.

• References:
  RFC 512, RFC 516, RFC 533.

[RFC 535] Comments on File Access Protocol.

[RFC 536]

• Never issued.

[RFC 537] Announcement of NGG meeting-JULY 16-17.

[RFC 538] Traffic Statistics (June 1973).

• Updated by:
  RFC 556.
• Updates:
  RFC 522.

[RFC 539] Thoughts on the Mail Protocol Proposed in RFC 524.

• References: RFC 524.

[RFC 540]

• Never issued.

[RFC 541]

• Never issued.

[RFC 542] File Transfer Protocol for the ARPA Network.

• References: RFC 354, RFC 454, RFC 495.

[RFC 543] Network Journal Submission and Delivery.

[RFC 544] Locating On-Line Documentation at SRI-ARC.

[RFC 545] OF WHAT QUALITY BE THE UCSB RESOURCE EVALUATORS? A Response to "Feast of Famine".

• References:
  RFC 369, RFC 519, RFC 531.

[RFC 546] TENEX Load Averages for July 1973.

[RFC 547] Change to the Very Distant Host Specification.

[RFC 548] Hosts Using the IMP Going Down Message.

[RFC 549] MINUTES OF NETWORK GRAPHICS GROUP MEETING.

[RFC 550] NIC NCP EXPERIMENT.

[RFC 551] NYU, ANL, and LBL Joining the Net.

[RFC 552] Single access to Standard Protocols.

[RFC 553] Draft design for a text/graphics protocol.

[RFC 554]

• Never issued.

[RFC 555] Response to Critiques of the Proposed Mail Protocol.

[RFC 556] Traffic Statistics.

• Updated by:
  RFC 566.
• Updates:
  RFC 538.

[RFC 557] Revelations in Network Host Measurements.

• References:
  RFC 392, RFC 415.

[RFC 558]

• Never issued.

[RFC 559] Comments on the new TELNET Protocol and its Implementation.

[RFC 560] Remote Controlled Transmission and Echoing Telnet Option.

[RFC 561] Standardizing Network Mail Headers.

• Obsoleted by: RFC 733.

[RFC 562] Modifications to the Telnet Specification.

• Updates:
  RFC 495.
• References:
  RFC 513, RFC 529.

[RFC 563] Comments on the RCTE TELNET Option.

• References:
  RFC 357, RFC 560.

[RFC 564]

• Never issued.

[RFC 565] Storing Network Survey Data at the Datacomputer.

[RFC 566] Traffic Statistics (August 1973).

• Updated by:
  RFC 579.
• Updates:
  RFC 556.

[RFC 567] CROSS-COUNTRY NETWORK BANDWIDTH.

[RFC 568] Response to RFC 567 -- Cross-Country Network Bandwidth.

[RFC 569] NETED: A Common Editor for the ARPA Network.

[RFC 570] Experimental Input Mapping Between NVT ASCII and UCSB Online System.

• Updates:
  RFC 216.

[RFC 571] Tenex FTP Problem.

[RFC 572]

• Never issued.

[RFC 573] Data and File Transfer - Some Measurement Results.

[RFC 574] Announcement of a Mail Facility at UCSB.

[RFC 575]

• Never issued.

[RFC 576] Proposal for Modifying Linking.

[RFC 577] Mail Priority.

[RFC 578] Using MIT-MATHLAB MACSYMA From MIT-DMS Muddle - An Experiment in Automated Resource Sharing.

[RFC 579] Traffic Statistics.

• Updated by:
  RFC 586.
• Updates:
  RFC 566.

[RFC 580] Note to protocol designers and implementers.

[RFC 581] Corrections to RFC 560 - Remote Controlled Transmission and Echoing Telnet Option.

[RFC 582] Comments on RFC 580 - Machine Readable Protocols.

[RFC 583]

• Never issued.

[RFC 584] Charter for Arpanet Users Interest Working Group.

[RFC 585] Arpanet Users Interest Working Group Meeting.

[RFC 586] Traffic Statistics.

• Updated by:
  RFC 601.
• Updates:
  RFC 579.

[RFC 587] Announcing New Telnet Options.

[RFC 588] London Node is now up.

[RFC 589] CCN NETRJS SERVER MESSAGES TO REMOTE USER.

[RFC 590] Multics Address Change.

[RFC 591] Addition to the Very Distant Host Specification.

[RFC 592] Some Thoughts on System Design to Facilitate Resource Sharing.

[RFC 593] Telnet and FTP Implementation Schedule Change.

[RFC 594] Speedup of Host-IMP Interface.

[RFC 595] Some Thoughts in Defense of the TELNET Go-Ahead.

[RFC 596] Second Thoughts on Telnet Go-Ahead.

[RFC 597] Host Status.

[RFC 598] RFC Index - December 5, 1973.

[RFC 599] UPDATE ON NETRJS.

• Obsoleted by:
  RFC 740.
• References:
  RFC 189, RFC 283, RFC 307, RFC 338, RFC 468.