# Filter criteria for landmark databases

The following table describes the `Filter` object properties for `GetList` calls that retrieve information about landmark databases.

Table: Filter object properties for a database search
Property | Description | Type | Value
--- | --- | --- | ---
`[Filter.DbProtocol]` | Specifies the protocol for accessing databases. If this property is specified, `GetList` returns a list of all the databases that use this protocol. If the protocol is not specified, `GetList` returns a list of all the available databases. | string | For example: `"file://"`