Clarified left-flanking and right-flanking.

Say explicitly that the beginning and end of line
count as whitespace for purposes of this definition.

Otherwise the opener in `_foo_` is both left and right
flanking, as @jmendeth pointed out.

Closes #310.

1 files changed, 6 insertions, 4 deletions

diff --git a/spec.txt b/spec.txt
index 3c1f712..c2a867d 100644
--- a/spec.txt
+++ b/spec.txt
@@ -4583,14 +4583,16 @@ characters that is not preceded or followed by a `_` character.
 A [left-flanking delimiter run](@left-flanking-delimiter-run) is
 a [delimiter run] that is (a) not followed by [unicode whitespace],
 and (b) either not followed by a [punctuation character], or
-preceded by [unicode whitespace] or a [punctuation character] or
-the beginning of a line.
+preceded by [unicode whitespace] or a [punctuation character].
+For purposes of this definition, the beginning and the end of
+the line count as unicode whitespace.
 
 A [right-flanking delimiter run](@right-flanking-delimiter-run) is
 a [delimiter run] that is (a) not preceded by [unicode whitespace],
 and (b) either not preceded by a [punctuation character], or
-followed by [unicode whitespace] or a [punctuation character] or
-the end of a line.
+followed by [unicode whitespace] or a [punctuation character].
+For purposes of this definition, the beginning and the end of
+the line count as unicode whitespace.
 
 Here are some examples of delimiter runs.