WRD relation types

WRD supports four basic entity types: objects, attachments, links and domains. All basic types support adding additional attributes and can have an explicit lifetime: creationdate (when the object is considered to start existing) and a limitdate (when the object no longer exists)

By default WRDType::CreateEntity will set the creationdate to the current time and limitdate to MAX_DATETIME but you can override these values at creation or change them later. An entity is considered to 'exist' if its creationdate <= the current time and the current time < limitdate.

WRDType::RunQuery and WRDType::Search will not show non-existent entities unless a specific historymode option is set.

An entity whose limitdate is in the past is considered 'closed'. It is not removed from the database by WRD - applications will generally automatically or manually eventually delete the closed entities.


An object is an entity with an independent existence. It is generally used to model persons, organizations and tangible 'real world' things.


An attachment models a 'Has A' relationship and is connected to another entity (which is considered its 'left side entity'). For example, 'requested a brochure' would often be modelled by an attachment.

An attachment entity type can only connect to a predefined entity type. Eg, if define an attachment to connect to a Person, it can't connect later to eg. a Car (unless these types inherit from each other)

If an attachments left side entity is deleted (as opposed to being closed), the attachment itself is also deleted.

Attachments were previously known as 'classifications'. Some old WRD applications may still use this term.

Persons and organizations

WRD_PERSON and WRD_ORGANIZATION are standard types which are always present in a WRD schema. WRD_PERSON has a lot of standard fields (eg WRD_GENDER, WRD_LASTNAME) to properly supply data for generated fields such as WRD_FULLNAME and WRD_SALUTE_FORMAL.

WRD_ORGANIZATION has only one extra standard field (WRD_ORGNAME) for the name of the organization field.

Both person and organization types derive from the WRD_RELATION type which defines a readonly WRD_TITLE field and can be used in circumstances in which you need to refer to either an organization or a person (eg as an account type for logins). Any fields added to the WRD_RELATION type will appear in both WRD_PERSON and WRD_ORGANIZATION.

The WRD_TITLE defined by WRD_RELATION is set to the WRD_FULLNAME for persons and to WRD_ORGNAME for organizations. To modify the WRD_TITLE of these types you need to modify either the WRD_ORGNAME (for organizations) or the fields that make up the full name field (WRD_GENDER, WRD_CALLINGNAME, WRD_LASTNAME etc)


A link is similar to an attachment, but connects two other entities. An 'is employee of' is an example of a link (with a person on its left side, and an organization on its right side.)

A link can only connect predefined entity types, but its left and right sides do not need to be of the same type. If either connected entity is deleted, the link is deleted too.


A domain is similar to an object but usually used for user-managed 'short' selection lists. Domains implicitly have a 'wrd_title' and 'wrd_ordering' attribute.

Domain values can be organized in a tree structure by using their 'left side entity' to point to their parent value - but this will cause deletion of a parent value to also cascade to all its children.

Selecting relation types

Array attributes versus attachments

It's not always immediately obvious whether to model something as an array attribute or an attachment. Array attributes are simpler to manage and to build Tollium interfaces for but are not as flexible as an attachment.

You should choose an attachment if:

You should choose an array if: