Constant is an attribute which indicates zero derivative of a symbol with respect to all parameters.
Constant is used by Dt.
Functions f[ ... ] are taken to have zero total derivative if f has attribute Constant.
Mathematical constants such as Pi have attribute Constant.
See The Mathematica Book: Section 2.5.3 and Section 3.5.2.
THIS IS DOCUMENTATION FOR AN OBSOLETE PRODUCT.
SEE THE DOCUMENTATION CENTER
FOR THE LATEST INFORMATION.