1. A method of propagating parameter definitions between computer elements, the method being implemented by a computer system and comprising: selecting a sub-routine to be called by a calling unit; determining whether a definition for a parameter in the selected sub-routine is known to the calling unit using a computer processor, the calling unit also containing a definition for a parameter; incorporating the definition for the parameter in the selected sub-routine that are unknown to the calling unit into the calling unit using the computer processor; executing the process of the calling unit using the computer processor; and binding the definition for the parameter in the sub-routine to the definition of the parameter contained in the calling unit using the computer processor, such that: the binding is based on contexts in the calling unit; and the parameter definition remains available to the calling unit after executing the process.