EXT meaning in Military and Defence ?

Answer: What is Exterior mean?

In topology, the exterior of a subset S {\displaystyle S} of a topological space X {\displaystyle X} is the union of all open sets of X {\displaystyle X} which are disjoint from S . {\displaystyle S.} It is itself an open set and is disjoint from S . {\displaystyle S.} The exterior of S {\displaystyle S} in X {\displaystyle X} is often denoted by ext X ⁡ S {\displaystyle \operatorname {ext} _{X}S} or, if X {\displaystyle X} is clear from context, then possibly also by ext ⁡ S {\displaystyle \operatorname {ext} S} or S e . {\displaystyle S^{\operatorname {e} }.}

reference

Full Form	Category
Exeter	Airport Code
Extract Resources Limited	Business
Extract Resources Ltd	Business
Extension File	Computing
e-Mail Text	Computing
Zaw	File Type
Escalade Crossover Truck	General
Executive Touring	General
EXTended file system	Information Technology
Extend	Medical
Extremity	Medical
Extremities	Medical
Emergency X-ray Technician	Medical
Exterior	Military and Defence
Exeter, England, UK	Regional
Exton Station (SEPTA Regional Rail- AMTK)	Regional
Experiment Terminal	Space Science
Extension	Space Science
External	Space Science