The ANDSF-SN is composed of six labels. The last three labels shall be "pub.3gppnetwork.org". The second and third labels together shall uniquely identify the PLMN. The first label shall be "andsf".
The ANDSF-SN is derived from the IMSI or Visited PLMN Identity as follows:
"mnc" and "mcc" serve as invariable identifiers for the following digits.
When contacting Visited ANDSF (V-ANDSF), the <MNC> and <MCC> shall be derived from the Visited PLMN Identity as defined in clause 12.1.
When contacting Home ANDSF (H-ANDSF), the <MNC> and <MCC> shall be derived from the components of the IMSI defined in clause 2.2.
In order to guarantee inter-PLMN DNS translation, the <MNC> and <MCC> coding used in the "andsf.mnc<MNC>.mcc<MCC>.pub.3gppnetwork.org" format of the ANDSF-SN shall be:
If there are only 2 significant digits in the MNC, one "0" digit shall be inserted at the left side to fill the 3 digits coding of MNC in the ANDSF-SN.
As an example, the ANDSF-SN OI for MCC 345 and MNC 12 is coded in the DNS as:
<MNC> = 3 digits
<MCC> = 3 digits