General Validity Constraints
This section specifies the validity constraints that are enforced on contact data. These constraints are intentionally relaxed for reasons of compatibility with existing data. Integrators are encouraged to ensure a higher data quality at data entry than strictly enforced by Address Book servers.
- Maximum number of contacts per address book: 5000
- Maximum number of categories per address book: 1000
- Maximum number of fields per contact (including hidden fields): 48
- Maximum number of categories (including system categories) a contact can be in: 32
- Maximum length of field data (for structured fields total of all components): 4095
- Maximum length of a category name in UTF-8 bytes: 255
- Category name cannot be empty, and it cannot contain any of the following characters: slashes, @, colons, semi-colons, brackets, parenthesis, less-than or greater-than signs, spaces, commas, single or double quotes.
- Anniversaries and Birthdays with the
yearcomponent specified are limited to the years 1902 to 2037. - Contact must contain at least one of the following fields or components: first name, last name, nick name, company, email, phone, yahoo ID, skype id, irc id, icq id, goog id, msn id, aim id, qq id or pending email/yid (hidden from the XML/JSON API)
- Contact can contain at most one field of type
yahooid. - No two contacts in the address book can have a
yahooidfield with the same value.