$readonly - Read-only Fields

This keyword marks a field as being read-only for all users. This means that, although the value of the given field will be displayed to anyone when accessing the details of an instance, that value cannot be edited - i.e., updated. The data input box for entering the value of a field built with the $readonly keyword will be greyed out when displaying the field at the instance level and the stored value cannot be changed.

Usage:

$readonly

Examples:

The video included below shows the behaviour of a field built with the $readonly keyword at the instance level: