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[This was included as a self-decoding answer in the posting of Exercise
#13; see exercise.013]

Answers to Around the Bend #13:

(a) No. (b) No.  In other words, a blank line will produce a \par if
and only if endline characters are present and have catcode 5. It is
interesting to note that two consecutive endline characters are not
translated simply to \par, but to <space>\par.  (The space will
disappear in some circumstances, e.g., after a control word, according
to TeX's normal scanning rules.) This is the reason (or at least one
reason) that a \par operation must perform an implicit \unskip
operation. There was also a recent post to comp.text.tex by Donald
Arseneau to point out the problem with someone's delimited-argument
macro definition:

  \def\something#1.\par{<do something with #1>}

The delimiter string ".\par" did not match the actual text

  ... some text.
  <blank line>

because of the space token following the period..