What is balanced party line standard in data communications?

Absolute gain - Access control - Acceptance pattern - Access time - Acoustic coupler - Acquisition - Asymmetric Digital Subscriber Line - Adaptive communications - Adder - Adjacent-channel interference - Alarm sensor - Aliasing - Allied Radio - Alternate party - Alternating current - AM radio - Amateur radio - Ambient noise level - American Radio Relay League (ARRL) - AMI - Ammeter - Amperage (see Current) - Ampere - Amplitude distortion - Amplitude modulation - Amplifier - Analog (disambiguation) - Analog computer - Analog decoding - Analogue switch - Analog to digital converter - Analysis of resistive circuits - Angular misalignment loss - Antenna - Antenna blind cone - Antenna effective area - Antenna gain - Antenna height above average terrain - Antenna noise temperature - Antenna theory - aperiodic antenna - aperture (antenna) - aperture illumination - Aperture-to-medium coupling loss - Apollo Guidance Computer - Arithmetic and logical unit - Armstrong oscillator - ARRL - Articulation score - Astable - Asynchronous communications system - Asynchronous operation - Asynchronous start-stop - Atmospheric duct - Atmospheric waveguide - Attenuation - Audible ringing tone - Audio system measurements - Audiophile - Automatic call distributor - Automatic data processing - Automatic gain control - Automatic link establishment - Automatic number identification - Automatic sounding - Automatic switching system - Autovon - Availability - Available line - Avalanche diode - Azimuth