The doc of split() says that maxsplit=-1 makes all possible splits as shown below:

... If maxsplit is not specified or is -1, then there is no limit on the number of splits (all possible splits are made).

But not just -1 but also other negative numbers make all possible splits as shown below. *It also occurs with rsplit():

v = 'one two three four'

print(v.split(maxsplit=-1))
print(v.split(maxsplit=-2))
print(v.split(maxsplit=-5))
print(v.split(maxsplit=-10))
# ['one', 'two', 'three', 'four']

So, the doc of split() should say that a negative number makes all possible splits as shown below:

... If maxsplit is not specified or is a negative number, then there is no limit on the number of splits (all possible splits are made).