Proposing a new base system as the current base system is flawed in many ways. According to some reddit users the current bases are defined as:
1 - Kissing / Making out
2 - Touching boobs
3 - Any kind of genital interaction except intercourse (manual or oral)
4 (Home base)- Sex
This newer system will reduce the ambiguity and allow "bros" to communicate their adventures more precisely and with less effort.
0.5 - Physical contact, may include holding hands and kissing of other non-intimate areas such as cheeks
1 - Kissing (Lips)
1.5 - Touching/groping boobs but over the clothes
2 - Touching/groping boobs
2.5 - Touching/groping the genitals but over the clothes
3 - Handjob/fingering (not necessarily to completion)
3.5 - Oral sex
4 (Home base)- Sex (As it has always been)
After this point it ceases being linear and splits off based on the individual/couple's preferences. Meaning they can have one, none or both of these bases covered
5A - Anal sex (A for anal)
5B - Period sex (B for blood)
There can also be progressions of 0.25 between these bases if one partner does this but the other does not reciprocate.