MT4 and Libraries

 
Hello MT4 Folks,

If I wanted to created a new library, is that considered an Expert or a Custom Indicator? At First i tried it as a script but thats not right because scripts cant be compiled.

Thanks for your Time
EK
 
see our samples.
there are in the experts/libraries directory library source stdlib.mq4, library executable stdlib.ex4;
in the experts/include directory appropriate header file stdlib.mqh
see our scripts with line "#include <stdlib.mqh>" - they call some library functions imported and defined in the stdlib.mqh