EDI X12 Field Mapping Specification Worksheet

How to use the worksheet

Work through the partner's implementation guide segment by segment. For inbound documents such as the 850, the ERP field is the target where the value will be stored. For outbound documents such as the 855, 856 and 810, the ERP field is the source. Choose a rule type for each row: direct copy, constant, lookup against a cross-reference, format change, concatenation of fields, or a conditional rule. Mark the usage as mandatory, optional or conditional exactly as the guide states.

• One worksheet per transaction set and direction
• Capture qualifier values for N1, REF and DTM loops
• Record max length so truncation rules are explicit
• Put every default and exception in the notes column

Common mistakes

Do not skip segments that look optional: partners often require them in practice. Do not leave lookup behavior undefined, for example what happens when a ship-to code has no cross-reference. Decide whether the document is rejected, held for review or sent with a default. Be explicit about quantities and prices: X12 uses explicit decimals in most quantity and price elements but implied decimals in monetary totals such as TDS01, and mixing these up causes valuation errors in both directions.