(1) (
All 
Time 
Low)  The lowest price of an asset in a market or exchange.  Contrast with 
ATH.
(2) (
Active 
Template 
Library)  A set of software routines from Microsoft that provide the basic framework for creating ActiveX and COM objects.  Stemming from the standard template library (STL) that comes with C++ compilers, ATL includes an object wizard that sets up primary structure of the objects very quickly.  See 
COM and 
ActiveX.