David W. Lambert <lambertdw@corning.com> added the comment:

I disagree.  You propose to examine the trees but ignore the forest.
The perspective programmer needs to understand what is a file.


Could you be more specific about what parts of my comments you disagree with? The current documentation leaves open the possibility of someone thinking that random access doesn't apply to text files, getting errors when entering the apparently legal, but in reality not, 'b', and that '+', 't+', and 'b+' are legal whereas they require a r, w, or a.

I know this bit of documentation has been stable for years, but in doing some writing I got tripped up by trying to write an example using just '+', despite being very knowledgeable about Python. At that pointI experimented with the various combinations and compared the reality against the documentation. What I ended up doing is splitting the table in two and listing the + combinations explicitly:
Text or Binary:
t       text
b       binary

Read, Write, or Append:
r       beginning, read
w       beginning, write
a       end, write
r+      beginning, read/write
w+      beginning, read/write
a+      end, read/write


--

        --- Mitchell