What we need to know to design and manufacture a compression spring:

Free length (F/L) Load in lbf of (kgf) at loaded length (L/L), Rate lbf load per inch (kgf per min), Maximum compression. Maximum solid length. Diameter, maximum outside (O/D) minimum inside (I/D) or mean diameter (M/D).

Right Hand or left hand wound, if essential. Type of ends. Material and finish.  Tolerances and special working conditions.

What we need to know to design and manufacture a tension spring:

Length overall (O/A) pull to pull (P/P) or body length (B/L). Diameter, maximum outside (O/D), minimum outside (I/D). Mean diameter (M/D).

Right hand or left hand wound, if essential. Type of ends. Material and finish. Tolerances and special working conditions.