Every character you type in will be checked for possible transformation in the following order:
Combine Vietnamese accent marks if possible
Change numbers to characters if possible (turn on/off in Advanced control panel)
Combine foreign characters if possible (turn on/off in Language control panel)
Apply autoexpansion level 1 macros if possible (turn on/off in Macro combo box in Main control panel)
Apply autoexpansion level 2 macros if possible (turn on/off in Macro combo box in Main control panel)
Apply lazy syllable macros if possible (turn on/off in Macro combo box in Main control panel)
Change characters to numbers if possible (turn on/off in Advanced control panel)
Apply shorthand macros if possible (turn on/off in Macro combo box in Main control panel)
Apply Hán Nôm macros if possible (run Hán Nôm dialog from the Run menu in Main control panel)
Apply remap macros if possible ( Main control panel → Typing Method → Remap)
Thus if you defined a' to be
á in Vietnamese (see Main control panel → Typing Method → Viet Chars)
ά in Greek (see Language control panel → Enable Greek)
then only the first definition would apply: typing a' gives you á. This is because step 1 is checked before step 3.
The users can control what steps to be checked by selecting or enabling appropriate options.
Step 9 (Hán Nôm) is active only when the user runs the Hán Nôm Manager: Main control panel → Run menu → Typing HanNom