Spring Elements (CELASi) in NASTRAN

[struclearner]

Dears,

NASTRAN has 4 different Spring Elements, CELAS1, CELAS2, CELAS3 and CELAS4. One difference between these elements is, how these are defined, by mentioning to PID or specifying K (Stiffness) values.
I could not find the mentioning of any other difference between these elements in NASTRAN User Guide. Are these elements, only differ in their formulations?
I will appreciate your input regarding the usage of these different Spring Elements and the difference between these.

Regards & Thanks

 

[crostolo]

..from the Quick Reference Guide

CELAS1, Defines a scalar spring element
CELAS2, Defines a scalar spring element without reference to a property entry
CELAS3, Defines a scalar spring element that connects only to scalar points
CELAS4, Defines a scalar spring element that is connected only to scalar points, without reference to a property entry