Terry J. Reedy added the comment:
The inconsistency might be a residue of the transition from 2.x. But the 'r'
versus 'rt' confusion originates in the code and signature. The text 't'
default is built into the code, while the read 'r' default is in the 'mode=r'
part of the signature.
If
New submission from Facundo Batista :
This is mostly a confusion about 'r' being a synonym of 'rt', while it's more
explicit if we consider 'r' as one default, and 't' as other (as other parts of
the documentation do).
Doing `help(open)` we get:
mode is an optional string that specifies
