Figuring out which bus to take was easy as there isn't much of a choice. Only one proper highway out of Huay Xai - to Luang Namtha - & only 2 buses a day, when the driver thinks it is 09:00AM or 11:30AM, which might not be quite the same as what you think. This would be the only bus ride where full name, nationality & passport no. had to be recorded in English on the ticket:
At all other bus stations & boat offices, the following would happen without fail...
staff: seu1? (name?)
cat: (says cat name)
cat: koi4 bpen1 fa1 lang1 (I am a farang)
staff: !! (scribbles something in Lao & hands over ticket)
Examples of the 'something in Lao':
From top to bottom:
- [1 & 6] dtor3 dtaa3 (ต 'dt' for 'eye') - slash - thor2 thung2 (ท 'th' for flag), an abbreviation for dtaang1 bpa1 thet4 (lit. foreign)?
-  dtaang1 bpa1 thet4
-  phasaa angkit (lit. English language) - cat asked if khian2 pha1 saa2 ang1 kit2 dai4 bor4 (can write it in English?), & the staff responded by writing 'phasaa angkit' as its name HAHAHA!
-  no idea
-  khaek4 ying2 (lit. guest female)