Attributes must have an associated syntax and follow the appropriate format before they can be added to the file . Each attribute has a syntax defined by a two or three letter symbol. The syntax describes the nature of the information stored in the attribute. When you add a new attribute to the slapd.at.conf file, you must give it a syntax definition. Searches are usually not performed on this attribute.
Data stored in ces attributes are case sensitive in searches.
Data stored in cis attributes are not case sensitive in searches. Use this syntax for values where case is irrelevant. Most attributes are of the cis syntax and allow the end users of Directory Server to easily complete searches without needing to know the case of what they are searching for. Most commonly tel is used for telphone , fax , and pager numbers. Data stored in the tel attribute is not case sensitive in searches.