A computer-implemented method of generating a form definition for a user interface form (108, 200) for transmission to a user interface module, comprising: receiving a form request comprising form identification data identifying a requested form; retrieving from a database: form definition data for the requested form based on the form identification data, wherein the form definition data includes a plurality of data elements defining form elements and specifying values for properties of the form elements; and at least one override data element defining an override, the override data element specifying an override condition for applying the override and one or more form data modifications, wherein the override data element is associated with a given form element, the form data modifications defined for the override including one or more override values for one or more properties of the associated form element; generating form instance data, the form instance data comprising a data description of the form based on the retrieved form definition data, as modified based on the at least one override data element, the generating comprising, for the, or each, override data element: determining whether the override condition defined for the override is fulfilled based on a control parameter controlling applicability of the override; in response to determining that the override condition is fulfilled, applying the form data modification(s) defined for the override to the retrieved form definition data, wherein applying the form data modification(s) comprises setting one or more properties of the associated form element to corresponding override values specified in the override data element; and wherein the method further comprises outputting the form instance data to the user interface module for generation of a user interface form based on the form instance data. receiving a form request comprising form identification data identifying a requested form; retrieving from a database: form definition data for the requested form based on the form identification data, wherein the form definition data includes a plurality of data elements defining form elements and specifying values for properties of the form elements; and at least one override data element defining an override, the override data element specifying an override condition for applying the override and one or more form data modifications, wherein the override data element is associated with a given form element, the form data modifications defined for the override including one or more override values for one or more properties of the associated form element; form definition data for the requested form based on the form identification data, wherein the form definition data includes a plurality of data elements defining form elements and specifying values for properties of the form elements; and at least one override data element defining an override, the override data element specifying an override condition for applying the override and one or more form data modifications, wherein the override data element is associated with a given form element, the form data modifications defined for the override including one or more override values for one or more properties of the associated form element; generating form instance data, the form instance data comprising a data description of the form based on the retrieved form definition data, as modified based on the at least one override data element, the generating comprising, for the, or each, override data element: determining whether the override condition defined for the override is fulfilled based on a control parameter controlling applicability of the override; in response to determining that the override condition is fulfilled, applying the form data modification(s) defined for the override to the retrieved form definition data, wherein applying the form data modification(s) comprises setting one or more properties of the associated form element to corresponding override values specified in the override data element; determining whether the override condition defined for the override is fulfilled based on a control parameter controlling applicability of the override; in response to determining that the override condition is fulfilled, applying the form data modification(s) defined for the override to the retrieved form definition data, wherein applying the form data modification(s) comprises setting one or more properties of the associated form element to corresponding override values specified in the override data element; and wherein the method further comprises outputting the form instance data to the user interface module for generation of a user interface form based on the form instance data.