is an attribute that, once assigned, prevents modification of any attributes of a symbol.


  • The attribute Locked, by itself, only affects whether attributes can be changed, not other properties of the symbol.
  • Locked is typically used in combination with Protected to prevent any further modification of a symbol.


open allclose all

Basic Examples  (2)

List has attribute Locked:

Protect and lock the symbol f:

Properties & Relations  (3)

The attribute Locked, once set, cannot be removed:

By itself, the attribute Locked does not prevent adding definitions to a symbol:

However, no new attributes can be added:

If a symbol is protected and locked, its definitions can no longer be changed:

Introduced in 1988