Field Types in a Table

Every field type a table column can be, grouped as the field picker groups them: basic, connected, computed and system. Covers formats, which fields are read-only, and the caps a table enforces.

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On this page

Choose the field by the question
Basic
Connected
Computed
System
Formats
Defaults
What you cannot type into
Caps
Where to go next

Every column in a table is a field, and a field has exactly one kind. The kind decides what the cell accepts, which editor opens when you click it, whether you can type in it at all, and what a formula is allowed to do with it. There is no second storage type to pick underneath.

Open the field picker from the + at the right end of the header row, or from the Fields rail. It groups the kinds four ways.

Choose the field by the question#

If you need to…	Start with…
Store something a person, feed, CSV, or API writes	A Basic field
Point this row at another record	A Relation
Bring back or summarise values from related rows	Lookup, Rollup, or Count
Calculate from this row or related rows	A Formula
Show who or when without storing another value	A System field

The key distinction is stored versus computed. Basic and relation values are inputs. Lookup, rollup, count, formula, and system values are outputs and cannot be typed into directly.

Basic#

These hold values you (or a feed, or a CSV import) put there.

Kind	What it holds
Text	A single line of text.
Long text	Multiple lines of text, edited in a larger box.
Number	A number, shown plainly or as currency, a percentage, or a duration.
Checkbox	Ticked or not.
Date	A calendar date.
Date & time	A date with a time of day.
Select	One option from a list you define.
Multi-select	Any number of options from a list you define.
Status	One option, grouped into not started, in progress, and complete.
URL	A link, validated and clickable.
Email	An email address, validated and clickable.
Phone	A phone number.
Rating	A score out of a maximum you choose.
User	One or more people from this workspace.
Auto number	A number assigned in order as rows are created, with an optional prefix.
Attachment	Files kept with the row, in the order you arrange them.
JSON	Arbitrary structured data.

Select, multi-select and status cells store an option's identity rather than its text, so renaming an option or changing its colour is a settings change and rewrites nothing. Options are defined on the field, and a value that is not one of them is rejected rather than quietly added.

Connected#

These reach other rows.

Kind	What it does
Relation	Links to rows in another table, or in this one.
Lookup	Shows a field from the rows a relation points at.
Rollup	Summarises a field across the rows a relation points at.
Count	Counts the rows a relation points at.

See Relations between tables and Lookups, rollups and counts.

Computed#

Kind	What it does
Formula	A calculation over this row, and over the rows its relations point at.

Lookup, Rollup and Count are, underneath, formulas that BankSync writes for you from the choices you make in their configurator. That is why any of them can be opened as a formula and taken over by hand. See Formulas.

System#

These come from the row's own history. They appear the moment you add them and are never typed into.

Kind	What it shows
Created time	When the row was created.
Last edited time	When the row last changed.
Created by	Who created the row.
Last edited by	Who last changed the row.

Formats#

A format decides only how a value is displayed. Changing one is instant, lossless and reversible, because the stored value never moves.

Number fields render as a plain number, a currency (pick the code — USD, AUD, GBP), a percentage, or a duration. You choose the decimal places.
Date fields render as ISO (2026-01-31), medium (31 Jan 2026), long (31 January 2026), US numeric (01/31/2026), EU numeric (31/01/2026) or relative (3 days ago).
Date & time fields offer ISO, medium, long, numeric and relative.
Text fields render as plain text, a link, or an email address.

Formats follow the result, not the kind, so a formula that produces a number formats as currency exactly like a number field does.

Defaults#

A field can carry a default that fills in when a row is created. Two kinds:

A fixed value — Status = Not started, Currency = AUD.
An expression, evaluated once at creation — today(), or dateAdd({fld:invoice_date}, 30, "days") for a due date thirty days out.

Three rules worth knowing, because they are what make a default safe to leave switched on:

A default fills a cell you did not supply. Clearing a cell on purpose keeps it empty — a default never overwrites a blank you chose, so a field with a default is still a field you can leave empty.
An expression default is evaluated once, when the row is created. Afterwards the cell is an ordinary value you can edit, and it does not change when the fields it read change. That is the difference between a default and a formula, which stays live forever.
Defaults apply to rows you add in the grid, through the API, and from a CSV import. They never apply to rows written by a feed. A feed is a mirror of what your bank sent; filling a gap there would invent data and attribute it to the institution.

If an expression default cannot be worked out — it references a field that is not filled in yet, say — the cell is simply left empty. Adding a row never fails because a default did not work out.

What you cannot type into#

Some cells are read-only in the grid, on the API, in CSV import and on feed writes alike. They are not locked to protect you from yourself; there is simply nowhere for a typed value to go.

Read-only	Why
Formula, Lookup, Rollup, Count	The value is derived. Writing one would be overwritten by the next recalculation, so it is refused.
Created time, Last edited time, Created by, Last edited by	Projected from the row's own metadata. There is no stored value to replace.
Auto number	Assigned in sequence when the row is created, so it stays unique and in order.

Relation and attachment cells are editable, but not by sending a value in a row write: links and files have their own identity and order, so they have their own operations. Putting them in a row write is refused with a typed error rather than quietly ignored.

A computed cell that is waiting to be recalculated says Recalculating rather than showing you a blank. A blank in a computed column always means the calculation genuinely produced nothing.

Caps#

These are refusals, not silent truncations. Crossing one fails the write and says which limit it hit.

Limit	Value
Fields per table	100
Options on a select, multi-select or status field	100
Files in one attachment cell	10
Bytes per uploaded file	25 MB
Links in one relation cell	100
Preview fields shown on a relation chip	2
Items a lookup may display	100
Size of one row's stored values	64 KB
Rows in one API batch insert	500
Table name	120 characters
Field label	120 characters