Based on the MSDN documentation, you will be able to find various values for this property.
See: http://msdn.microsoft.com/en-us/library/ff701725.aspx
Extracted from the documentation:
The level of confidence that the geocoded location result is a match.
Use this value with the match code to determine for more complete
information about the match.
The confidence of a geocoded location is based on many factors
including the relative importance of the geocoded location and the
user’s location, if specified. The following description provides more
information about how confidence scores are assigned and how results
are ranked.
If the confidence is set to High, one or more strong matches were
found. Multiple High confidence matches are sorted in ranked order by
importance when applicable. For example, landmarks have importance but
addresses do not.
If a request includes a user location or a map area (see User Context
Parameters), then the ranking may change appropriately. For example, a
location query for "Paris" returns "Paris, France" and "Paris, TX"
both with High confidence. "Paris, France" is always ranked first due
to importance unless a user location indicates that the user is in or
very close to Paris, TX or the map view indicates that the user is
searching in that area.
In some situations, the returned match may not be at the same level as
the information provided in the request. For example, a request may
specify address information and the geocode service may only be able
to match a postal code. In this case, if the geocode service has a
high confidence that the postal code matches the data, the confidence
is set to High and the match code is set to UpHierarchy to specify
that it could not match all of the information and had to search
up-hierarchy.
If the location information in the query is ambiguous, and there is no
additional information to rank the locations (such as user location or
the relative importance of the location), the confidence is set to
Medium. For example, a location query for "148th Ave, Bellevue" may
return "148th Ave SE" and "148th Ave NE" both with Medium confidence.
If the location information in the query does not provide enough
information to geocode a specific location, a less precise location
value may be returned and the confidence is set to Medium. For
example, if an address is provided, but a match is not found for the
house number, the geocode result with a Roadblock entity type may be
returned. You can check the entityType field value to determine what
type of entity the geocode result represents. For a list of entity
types, see Entity Types.