• They must be unique within an installation.

• They must begin with an alphabetic character (not the underscore).

• No special characters other than the underscore, dollar sign, and at symbol (@) are allowed for regular identifiers.

• The maximum length of a database name is 32 bytes. However, the name must be unique to 24 bytes (or the maximum file name length imposed by your operating system, if less than 24).

• Case significance (upper or lower) is determined by the settings for the database in which the object is created (Ingres or ANSI/ISO Entry SQL-92-compliant) and may differ for delimited and non-delimited identifiers).