Glossary · formdef

formdef uses one word per concept, in the code, in error messages and here.

Term	Meaning
form	A TanStack form instance, with its store.
values	What the form holds while it runs: `form.state.values`.
data type	The type of the values: the input type of the schema.
schema	The Standard Schema that validates a form.
config	The object `createForm` takes, or the `fields` and `layout` that `Fields` takes.
level	One object level of a config: its `fields` and its `layout`.
path	The name of a field while the form runs: `address.zip`, `contacts[0].name`. A key is one segment of it.
field entry	One entry under `fields`. It has one of four shapes.
leaf, object, array, custom	The four shapes of a field entry, marked by `widget`, `fields`, `item` and `render`.
item	One element of an array, and the key of an array entry that describes it.
widget	A component that takes `FieldOf<V>`, registered under `widgets`.
control	The element of a widget that a person operates: an input, a button, a list.
form component	A component registered under `formComponents` and placed by `{ component }` in a layout.
structure slot	One of `body`, `section`, `row` and `arrayFrame`: the four places where formdef renders markup of its own.
array frame	What renders the items of an array, with their add and remove controls.
layout entry	One entry of a `layout`: a name, a section, a row, a form component or an inline entry.
section, row	The two layout entries that group others.
inline entry	A `{ render }` entry in a layout.
registry	What `createRegistry` returns.
shadcn registry	The distribution of formdef's widgets for shadcn, always named with its qualifier.
base	The primitive library that shadcn components are built on; for formdef's widgets, Base UI.
validator key	A key of `validators`: `onChange`, `onBlurAsync` and the others.
error is due	The moment a widget shows a field's error: the field is invalid, and it was edited and left, or the form was submitted.
one call, own shell, plain TanStack	The three ways in.

Two words keep a second meaning where TanStack owns it: fields as the prop of a field group and as half of a form validator's result, and mode as TanStack's field mode next to validation.mode.