I am migrating to koha.I got a spreadsheet with the present data. I have found the marc21 tag info details for each column. eg. Accession Number 541##$e. I am using MarcEdit 's Delimited Text Translator. When I tried to map data and click Add argument, MarcEdit gives the following "Mapping Error." " Field / Subfield combinations must be defined at 245$a It appears that your intention is to create such a pair. If that's the case please click OK and update the mapping. If your data is not a field/subfield pair, click cancel to ignore this, as well as future messages. " But when I click ok, I get the same message, And when I click cancel cancel the data is added to the Arguments text area like : 0 541 ##$e 0 Please help me to proceed further. ​with thanks and regards Tanzeem