The Address Verification Code (AVC) provides information about the completeness of the input data, the level of verification that could be achieved, and the amount of change that was needed to reach that level of verification. It is made up of the following values:
e.g. V44-I44-P3-100 implies:
Verification Status = V (Verified)
Post-Processed Verification Match Level = 4 (Premise)
Pre-Processed Verification Match Level = 4 (Premise)
Parsing Status = I (Identified and Parsed)
Lexicon Identification Match Level = 4 (Premise)
Context Identification Match Level = 4 (Premise)
Postcode Status = P3 (Added)
Matchscore = 100 (Complete similarity)
The post-processed verification match level gives the level to which the input data matches the available reference data once all changes and additions performed during the verification process have been taken into account.
The pre-processed verification match level gives the level to which the input data matches the available reference data prior to any changes or additions performed during the verification process.
The lexicon identification match level gives the level to which the output data has some recognized form, through the use of pattern matching (e.g. a numeric value could be a premise number) and lexicon matching (e.g. ‘rd’ could be a ThoroughfareType, ‘Road'; ‘London’ could be a Locality)
The context identification match level gives the level to which the output data can be recognized based on the context in which it appears. This is the least accurate form of matching and is based on identifying a word as, for instance, a Thoroughfare based on it being preceded by something that could be a Premise, and followed by something that could be a Locality, the latter items being identified through a match against the reference data or the lexicon.
The matchscore indicates how much the input data has been changed during the verification process in order to achieve the post-processed verification match level. 100% means no changes have been made. Data additions are not measured by the matchscore, only changes. Generally a matchscore of 95 or above indicates only a character or two have been changed during the process. If the input data is less clean a threshold of 80 might be considered, since significantly larger changes to the input data will then be allowed. Please note that this value gives no indication of the level of verification, that is given by the post-processed verification match level.