variables (the LC_ALL, LC_TYPE, and LANG, in the order
of decreasing precedence) -- if the variables indicate
UTF-8, then the selected "IOEioA" are in effect
+ a 256 Set ${^UTF8CACHE} to -1, to run the UTF-8 caching code in
+ debugging mode.
+
+=for documenting_the_underdocumented
+perl.h gives W/128 as PERL_UNICODE_WIDESYSCALLS "/* for Sarathy */"
+
+=for todo
+perltodo mentions Unicode in %ENV and filenames. I guess that these will be
+options e and f (or F).
For example, C<-COE> and C<-C6> will both turn on UTF-8-ness on both
STDOUT and STDERR. Repeating letters is just redundant, not cumulative
X<-c>
causes Perl to check the syntax of the program and then exit without
-executing it. Actually, it I<will> execute C<BEGIN>, C<CHECK>, and
-C<use> blocks, because these are considered as occurring outside the
-execution of your program. C<INIT> and C<END> blocks, however, will
-be skipped.
+executing it. Actually, it I<will> execute C<BEGIN>, C<UNITCHECK>,
+C<CHECK>, and C<use> blocks, because these are considered as occurring
+outside the execution of your program. C<INIT> and C<END> blocks,
+however, will be skipped.
=item B<-d>
X<-d> X<-dt>
layer specification strings (which is also used to decode the PERLIO
environment variable) treats the colon as a separator.
-An unset or empty PERLIO is equivalent to C<:stdio>.
+An unset or empty PERLIO is equivalent to the default set of layers for
+your platform, for example C<:unix:perlio> on UNIX-like systems
+and C<:unix:crlf> on Windows and other DOS-like systems.
The list becomes the default for I<all> perl's IO. Consequently only built-in
layers can appear in this list, as external layers (such as :encoding()) need