This seems to be a bug from the original plan9. It catches my eye quite frequently in man pages.
For example, in man(1),
Man locates and prints pages of this manual named title in
the specified sections. Title is given in lower case. Each <- before Title
section is a number; pages marked (2S), for example, belong
to chapter 2. If no section is specified, pages in all sec-
tions are printed. Any name from the NAME section at the
top of the page will serve as a title.
Note that the space before Title on the second line is recognized as a normal space (1 space) instead of a sentence space (2 space), as in the following sentences.
Here is the source of the paragraph
.I Man
locates and prints pages of this manual named
.I title
in the specified
.IR sections .
.I Title
is given in lower case.
Each
.I section
is a number;
pages marked (2S), for example,
belong to chapter 2.
If no
.I section
is specified, pages
in all sections are printed.
Any name from the
.SM NAME
section at the top of the page will serve as a
.IR title .
The problem appears to be in the .IR macro, but I suspect it affects all font-alternation macros.
This seems to be a bug from the original plan9. It catches my eye quite frequently in man pages.
For example, in
man(1),Note that the space before
Titleon the second line is recognized as a normal space (1 space) instead of a sentence space (2 space), as in the following sentences.Here is the source of the paragraph
The problem appears to be in the
.IRmacro, but I suspect it affects all font-alternation macros.