% -*- Mode: TeX -*-

\beginSubsection{Syntax of Logical Pathname Namestrings}

\issue{PATHNAME-LOGICAL:ADD}
The syntax of a \term{logical pathname} \term{namestring} is as follows:
 
{\tt \lbracket\ \i{host} ":" \rbracket\ \lbracket\ ";" \rbracket\ 
\lbr\ \i{directory} ";" \rbr\ * \lbracket\ \i{name} \rbracket\ 
\lbracket\  "." \i{type} \lbracket\ "." 
\i{version} \rbracket\ \rbracket\/}

\noindent
\boxfig
{\advance\baselineskip by 2.5pt
\halign{\hskip\leftskip#\hfil&#\hfil\cr
\i{host}::$=$ \i{word} &\cr
\i{directory}::$=$ \i{word} $\vert$ \i{wildcard-word} $\vert$
\f{**} &\cr
\i{name}::$=$ \i{word} $\vert$ \i{wildcard-word} &\cr
\i{type}::$=$ \i{word} $\vert$ \i{wildcard-word} &\cr
\i{version}::$=$  \i{pos-int} $\vert$ \f{newest} 
$\vert$ \f{NEWEST} $\vert$ \f{*} &\cr
\i{word}::$=$ one or more uppercase letters, digits, and hyphens. &\cr
\i{wildcard-word}::$=$ one or more asterisks, uppercase letters, &\cr
  digits, and hyphens, including at least one asterisk, with no two
  asterisks adjacent.  &\cr
\i{pos-int}::$=$ \term{integer} {\tt > 0} &\cr
}}
\caption{Logical-pathname syntax}
\endfig
\indent 
The following information applies to the syntax.
\beginlist
\itemitem{\b{Host}}

\i{Host} has been defined as a \term{logical pathname} host 
by using \macref{setf} of \funref{logical-pathname-translations}.
The \term{logical pathname} host name \f{"SYS"} is reserved for the implementation.
The existence and meaning of \f{SYS:} \term{logical pathnames} 
is \term{implementation-defined}.
 
\itemitem{\b{Device}}
 
There is no device,
so the device component of a \term{logical pathname} is always \kwd{unspecific}.
%!!! Put this elsewhere? -kmp 12-May-91
No other component can be \kwd{unspecific}.  

\itemitem{\b{Directory}}

If a \term{semicolon} precedes the directories,
the \i{directory} component is relative, otherwise it is absolute.
\f{**} parses into \kwd{wild-inferiors}.
 
\itemitem{\b{Type}}

The \i{type} of a 
\term{logical pathname} for a \clisp\ source file is \f{"LISP"}.
  This should be translated into whatever type is appropriate in a physical
  pathname.
 
\itemitem{\b{Version}}

Some file systems do not have \i{versions}.  
\term{logical pathname} translation to such a file system ignores the 
\i{version}.  This implies that a program cannot rely on being able
to store more than one version of a file named by a \term{logical pathname}.
\f{*} parses into \kwd{wild}.  

\itemitem{\b{Wildcard-word}}

Each asterisk in a \i{wildcard-word} matches a sequence of zero or more characters.
The \i{wildcard-word} \f{*} parses into \kwd{wild},
the others parse into \term{strings}.
 
\itemitem{\b{Any other value}}
 
The consequences of using any value not specified here as a 
\term{logical pathname} component are unspecified.

\endlist 

In \i{words} and \i{wildcard-words} lowercase letters are translated to
uppercase.  The consequences of using other characters are unspecified.
The null string \f{""} is not a valid value for any component of a \term{logical pathname},
since \f{""} is neither a \i{word} nor a \i{wildcard-word}.

%This wasn't a valid reference.
%See ``Input/Output'' for parsing and file manipulation details.
\endissue{PATHNAME-LOGICAL:ADD}

\endSubsection%{Syntax of Logical Pathname Namestrings}