M stands for Manager level
SM for Senior Manager level
SE for Senior Executive level (partner)
At each level there is number next to it i.e. M1, M2, M3, which simply implies that how many years have you been in that cadre i.e. M3 implies three years in Manager cadre. Typical first year you are called M1, second year M2, third year M3 and so on so forth.
Same goes for SM, SE levels
Now, M3 is the level at which you typically can be considered for promotion into Senior Manager so you become SM1 and similry after SM3 you become SE1
But can also happen that instead you only become M4 and then M5...these are not promotions...just place holder and in a way to self-differentiate under performers from the crowd.
Salry band for Senior manager starts around the range indicated earlier 90 K upwards with car, bonus etc....I am not sure how high it can go...may be about 120 or 130K plus exras.
Hope it helps.........