### Validation Rules

AVI MetaEdit incorporates various set of rules which may be enforced or disabled while editing metadata. For instance AVI MetaEdit implements BEXT Coding History for AVI files in the IMIT LIST-INFO chunk. The original Coding History expression is defined by EBU Technical Recommendation R98-1999. For AVI MetaEdit and to extend the relevance of Coding History to video a new Coding History defintiion is provided in the IMIT Help documentation. Users may decide whehter they wish to follow the associated recommendations and requirements from US National Archives or Microsoft by enabled or disable rule sets in the Rules section of the preferences. For instance with coding history if these rules are disabled, the data entry can be performed within one large text field (as many audio applications do).
AVI MetaEdit responds to rules and recommendations outlined by EBU, Microsoft, and the U.S. National Archives in order to warn or prevent the user from entering metadata that does not comply with any validation rules. These rules may be disabled as needed but are recommended in order to facilitate the generation of standardized files. For each set of validation rules, AVI MetaEdit performs the following tests and displays any existing embedded metadata or changes in red if they do not follow the enabled rules or green if the changed value is acceptable to the selected rules.

### INFO (Microsoft definition)

#### Requirements

ICMD: The ICMD field must not contain line breaks.

#### Recommendations

ICRD: The ICRD field must be in YYYY, YYYY-MM, YYYY-MM-DD format or initiate with a YYYY-MM-DD formatted string and then include additional free text.

### U.S. National Archives recommendations

- IARL: IARL may not be empty and must be at least four characters long. IARL must start with two capital letters followed by a comma and then a space. The recommended formatting is to start with a two character country code (as expressed by ISO 3166-1), followed by a comma, space, and the organizational name. Example: "US, NARA"
- ICRD: If the INFO-LIST chunk is used, ICRD must follow ISO 8601

### Inheritance of Rules

Use of the U.S. National Archives recommendations assumes the use of AVI recommendations.
Use of the INFO recommendations assumes the use of INFO requirements.
Use of the AVI recommendations assumes the use of AVI requirements.