# Declare a Dynstruct Variable > [HTML Version](declare_a_dynstruct.htm) To enable the structure to be defined at runtime, an empty dynamic structure variable must be declared at compile time, using the type DYNSTRUCT**:** MAP1 ds, dynstruct \! scalar dynamic structure MAP1 DS2, DYNSTRUCT \! another As with other built-in types, the type name is case insensitive. Dynstructs are similar to dynamic X variables (X,0), except that they may be associated with—i.e. bound to—a structure definition. Until then, the structure is considered "uninitialized". Once the dynstruct variable has been bound to a defined structure, it behaves like a fixed-length instance of that structure. See [Reference / Usage](referenceusagedynamic.htm.md).