I.R.I.S. Cardiris Pro 5 - Manual (Page 67)

Cardiris TM 5 – User Guide
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The default custom fields can be extended with an unlimited
number of other custom fields.
To add a custom field to a card:

Open the card in card view.

Click the + sign next to Custom Fields. Or click Custom fields
on the Edit menu.

Click Add and enter the name of the custom field.
Note: avoid using semi-colons (;) and vertical bars (|) both in the
custom field name and in the content. These characters are forbidden.

Then click OK to confirm.
The custom field will be added to the standard database fields.