Regarding EDI info, visit X12.org/UNEDIFACT.org sites…you will get much better idea about what it does and also about the EDI Segments/structures (functional design).
you asked about the Templates,i think you are using pre webMethods/EDI 6.0 version (ie 4.6) …
There are some X12/UNEDIFACT templates available,which webMethods provided for us,so that we can load those (4010,3030,2010…)templates using Developer tool ,which will create us webMethods Record/Document structure and its ready for mapping to different formats(XML/IDOC…)
You can locate the sample EDI mapping from wmEDISample default Package provided by EDIModule.
HTH.
#webMethods#edi#Integration-Server-and-ESB