[latexrefman] When reading input @TeX{} converts sequences of read characters into a

[Karl Berry]

    I cannot understand why this is « sequences », not « the
    sequence ». 

Each token is created from a sequence of characters, thus, "sequences".
I found it confusing as written. I don't make changes for no reason.

Of course you're right that there is only one input stream. What caught
my eye was the duplication of the word "sequence(s)".

Looking at it again now, it might work better to just avoid "sequence"
for the character input, for example:

  @TeX{} converts the stream of characters from the input into a
  sequence of tokens ...
  
That said, do what you want :). It's not worth spending more time on.
--thanks, karl.