krb5_principal_intro (3) - Linux Man Pages
krb5_principal_intro: The principal handing functions.
krb5_principal_intro - The principal handing functions. A Kerberos principal is a email address looking string that contains two parts separated by The second part is the kerberos realm the principal belongs to and the first is a list of 0 or more components. For example
lha [at] SU.SE host/hummel.it.su.se [at] SU.SE host/admin [at] H5L.ORG
See the library functions here: Heimdal Kerberos 5 principal functions