Is Read-only hook

Use this hook to set a custom field to read-only. This hook is executed only once at form initialization. To set a field read-only if other fields are changed, use the When Field Changes hook to set the custom field to read-only. You can use the disable.fields() function.

Example:

function extern boolean ext.currency.is.read.only()
{
        return(txcomdll0001.is.currency.fixed(ext.currency))

}