837D experience required

Translate from xml document to 837D format Currently xml is translated into a format that would print on a pre-printed claim form using a dot-matrix printer ... so we have something like: (characters are placed in specific column ranges, form is exactly 67 lines long) X 1/1/2009 patient name office name patient address ofice address city state zip city state zip x x x no A blue cross blue cross address city state zip 056-88-9999 02/01/2009 D1045 80.00 02/01/2009 D1046 90.00 170.00 5405 x x Now in 837D has odd codes that prepend and append each field value... (example - i have made up the codes that prepend and append the fields below as and example. The spec is 200 pages) N3y!DATEOFCLAIMy7Y^ A3u8PATIENTNAMEiu8(^&% jhj&PATIENTADDRESSLINEBY61*&*^& and this list goes on and on Now my current developer tells me that according the the value of the field, that the code may change. This makes it more difficult to program. So I am looking for someone with experience in the 837D world.