Glossary of Terms

X

X Modem
This is a protocol for transferring files during direct dial-up communications. Xmodem has basic error checking to ensure that information isn't lost or corrupted during transfer; it sends data in 128-byte blocks. Xmodem has undergone a couple of enhancements: Xmodem CRC uses a more reliable error-correction scheme, and Xmodem-1K transfers data faster by sending it in 1,024-byte blocks.

X.680
Abstract Syntax Notation One (ASN.1): Specification of basic notation.

X.681
Abstract Syntax Notation One (ASN.1): Information object specification.

X.682
Abstract Syntax Notation One (ASN.1): Constraint specification.

X.683
Abstract Syntax Notation One (ASN.1): Parameterisation of ASN.1 specifications.

X.690
ASN.1 encoding rules: Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER).

X.691
ASN.1 encoding rules: Specification of Packed Encoding Rules (PER).

X.xxx
ITU X series recommendations - Data networks and open system communications.

xDSL
Generic name for the various Digital Subscriber Line services such as ADSL, VDSL etc.

Xon-xoff:
A communications protocol that synchronises modems and similar devices.

XYCLOPS 800 and 900
The PC add-in video telephone boards developed by Motion Media Technology.