Muban 77 and 78 - the answer

Shortly ago, I posted on two strange administrative villages only named Mu 77 and Mu 78. Since I just stumbled on yet another website which lists them - this time the one of TAO Phan Thong in Chonburi province, I tried once more to find any explanation on the meaning of these two villages. And this time I was successful - the subdistrict municipality Tha Kham in Chiang Mai also lists them, but unlike the previous cases it also add a note on them.

หมายเหตุ
หมู่ที่ 77 ทะเบียนบ้านกลางท้องถิ่นเทศบาล
หมู่ที่ 78 ทะเบียนบ้านกลางคนเดินทางไปต่างประเทศ

Note:
Mu 77 Central House registration of local municipality
Mu 78 Central House registration of people traveling outside the country

On another site Mu 78 is defined as ทะเบียนบ้านคนต่างด้าว which is even more clearly to understand - the registration of foreign residents. I am not sure what is the purpose of number 77, after some further googeling it seems this is used to register for missing persons which obviously cannot be assigned to any of the real villages.