1.2.840.113556.1.4.907 is defined in Draft-armijo-ldap-syntax-00 as:
CaseIgnoreString: 1.2.840.113556.1.4.905 Encoded as a Printable String (OID 1.3.6.1.4.1.1466.115.121.1.44)
Printable String 1.3.6.1.4.1.1466.115.121.1.44