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How to Prepare Local 9XX Fields Before a Koha Migration

Learn how to review local 9XX MARC fields before migrating to Koha, including old system IDs, item data, notes, branches, and vendor-specific fields.

May 19, 2026 4 min read

How to Prepare Local 9XX Fields Before a Koha Migration

Local 9XX fields can be some of the most important fields in a migration. They may contain old system identifiers, item data, acquisition notes, vendor references, branch information, or other local metadata.

They can also be messy.

Before migrating to Koha, review local 9XX fields carefully.

What are local 9XX fields?

MARC fields in the 9XX range are often used locally. Their meaning can vary from one system or library to another.

One library might use a 9XX field for item data. Another might use the same field for vendor notes, old system IDs, or migration markers.

Because these fields are local, they need project-specific review.

Why 9XX fields matter in Koha migrations

During migration, 9XX fields may help preserve:

old bibliographic record IDs;
item barcodes;
branch codes;
shelving locations;
item types;
call numbers;
prices;
acquisition notes;
collection codes;
withdrawn or lost statuses.

If these fields are ignored, important migration data may be lost.

If they are imported blindly, your new Koha catalogue may contain confusing or unnecessary local data.

First step: inventory the 9XX fields

Create a list of all 9XX fields present in the export.

For each field, identify:

field tag;
subfields used;
example values;
number of records using the field;
whether the field is bibliographic or item-related;
whether it should be preserved, mapped, transformed, or removed.

Common 9XX migration decisions

Decision	Example
Preserve	Old record ID needed for audit trail
Map	Branch name should become Koha branch code
Transform	Item type value needs conversion
Remove	Vendor processing note no longer useful
Review manually	Field contains inconsistent values

Item data in local fields

In many Koha migrations, item data is mapped into a Koha item field (commonly 952).

Check for:

barcode;
home branch;
holding branch;
item type;
shelving location;
call number;
copy number;
replacement price;
lost/withdrawn status.

Confirm that the values match Koha’s configured codes. For example, “Main Library” in the export may need to become MAIN in Koha.

Old system identifiers

Old record IDs can be useful after migration.

They can help:

trace records back to the legacy system;
troubleshoot migration differences;
match exports across multiple batches;
support audit or rollback work.

Decide whether old IDs should be preserved in a local field or used only during migration.

How MARCReady helps

MARCReady can flag local fields for review, identify repeated or empty subfields, and help reveal the structure so you can make safer migration decisions.

For CSV, Excel, TSV, and JSON files, Kai can also help identify columns that appear to contain local item or migration data.

MARCReady does not decide your local field policy. It helps reveal the structure so you can make informed decisions.