That part of the code that tells the compiler about
  an object before the compiler uses it.  A declaration
  causes the compiler to create the object or tells
  it where to look for the object.  A declaration has a
  position in the source code with both a start and an
  end, and can contain other declarations or references.
  It can be either a primary or associated declaration.
  You can cross-reference query declarations of a symbol
  by selecting Declaration for the Usage query attribute.