Choose where answers come from

For each output column, decide who supplies its value. This is the field’s fill setting. It is separate from the value’s type and the control’s widget.

The four kinds

Fill	Where the value comes from	What the labeler sees	Required by default
user	An answer on each record	An answer control	Yes
session	One answer for the whole input file	A setup question	Yes
copy	A source column	No answer control	No
timestamp	The app’s completion time	No answer control	No

user

This is the default. Omit fill for ordinary per-record questions.

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{ "name": "notes", "type": "text", "widget": "textarea", "required": false }

session

Ask once before labeling begins. Use it for the reviewer name, team, or guideline version.

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{ "name": "annotator", "type": "text", "display": "Your name", "fill": { "kind": "session" } }

The answer is added to every completed output row. It does not make untouched records count as started. If you declare cards, put setup questions in a card with scope: "session".

Download the reviewer-details project →

copy

Carry a value from input to output without asking the labeler to enter it.

{ "name": "id", "type": "text", "fill": { "kind": "copy" } }

from defaults to the output field’s own name. To rename a column, set it explicitly:

{ "name": "sourceId", "type": "text", "fill": { "kind": "copy", "from": "id" } }

The source and destination types must match. Copying a text ID into an integer field is rejected, even when the sample IDs look numeric. For nested data, keep the source and copied type definitions aligned.

See the source display and resulting CSV →

timestamp

Use a date field with fill.kind: "timestamp" to record when a record becomes complete. Later edits to a complete record update the timestamp.

{ "name": "labeledAt", "type": "date", "fill": { "kind": "timestamp" } }

There is no date picker for this field. Use an ordinary user-filled date field if the labeler must choose a date from the record.

Interactive vs derived

Do not set widget or shortcut on copy or timestamp fields: there is no control to render or focus. They can still be required if your project needs their values present.

A required copied field can leave a record incomplete when its source value is missing. The labeler cannot repair that source from the answer form; resolve the source problem before distribution.

What actually gets written

A completed output row combines the record’s entered answers, copied source values, session answers, and timestamps in output.fields order. Remaining files contain source records, not these partially completed output values.

Export behavior · Fill reference