This document is a description of a mapping from the X12N Implementation Guides to
an XML document which completely specifies the guides for the purposes of data translation.  
Some XML elements have been added to support a data translator.  At some point, I will write 
a XML schema to more precisely define the XML elements and valid values.

usage:  IG Usage field. S=Situational, N=Not Used, R=Required
data_type: STD type
min_len/max_len: STD
pos: segment position number
id: IG id
name: IG name
ref_des: reference designator
data_ele: Data Element
ref_des: Reference Designator
valid_codes: list of valid codes for the element or a pointer to the list
syntax: STD syntax dependency string, optional
