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this  Glossary & Acronyms    An electrical signal that varies
constantly in voltage, unlike a digital signal which varies
between two constant values (typically denoted as 0 and 1). The
value of the analog signal varies all the time during
transmission, whereas a digital signal changes only between two
set values without intermediate variations.  Asymmetrical
Digital Subscriber Line (ADSL) ADSL refers to a pair of modems
connected by a copper line that yields asymmetrical transmission
of data.  Asynchronous Transfer Mode (ATM) A way of transmission
where a start signal precedes individual characters and one or
more stop signals follow it. Due to this start/stop system,
delays may occur between characters. Also denotes the complete
system of protocols and equipment associated with cell-based
communications networks. These n