Recording something Allotmin does not have a field for

Every member has three spare fields you can name yourself. A membership number from the system you came off, a date of birth the council occasionally asks you to confirm, a car registration for the gate.

Turning one on

Settings → Members → give the field a label.

The label is the switch. A field with no label does not exist anywhere — not on the member form, not on their profile, not in the import, not in the export. Give it a name and it appears in all of those at once.

Showing it in the members list

That is a separate tick, because an association that labels one field usually wants one extra column, not three. Turn it on next to the label.

Why only three

Because a stated limit is the only honest answer to "can we have a fourth". Three real fields keep everything else working — they import, they export, they can be searched — and they stop the member record quietly growing a column per request until nobody can find anything.

If three is genuinely not enough, the Notes field on each member takes as much free text as you like.

They are just text

Whatever you put in them is stored as you typed it. A date of birth typed as 3/4/65 stays 3/4/65 — Allotmin does not do arithmetic with these, which means it also never refuses one for being in the wrong format.

Clearing a label

Clearing a label hides the field. It does not delete what is in it. Put the label back and everything is still there, which means a label cleared by accident costs you nothing.