ANSI Common Lisp  19 Filenames 19.2 Pathnames 19.2.2 Interpreting Pathname Component Values
19.2.2.4 Restrictions on Examining Pathname Components
The space of possible objects that a conforming program
must be prepared to read1
as the value of a pathname component
is substantially larger than the space of possible objects
that a conforming program is permitted to write1
into such a component.
While the values discussed
in the subsections of this section,
in Section 19.2.2.2 Special Pathname Component Values,
and in Section 19.2.2.3 Restrictions on Wildcard Pathnames
apply to values that might be seen when
reading the component values,
substantially more restrictive rules apply to constructing pathnames;
see Section 19.2.2.5 Restrictions on Constructing Pathnames.
When examining pathname components,
conforming programs should be aware of the following restrictions.
19.2.2.4.1 Restrictions on Examining a Pathname Host Component
19.2.2.4.2 Restrictions on Examining a Pathname Device Component
19.2.2.4.3 Restrictions on Examining a Pathname Directory Component
19.2.2.4.4 Restrictions on Examining a Pathname Name Component
19.2.2.4.5 Restrictions on Examining a Pathname Type Component
19.2.2.4.6 Restrictions on Examining a Pathname Version Component
19.2.2.4.7 Notes about the Pathname Version Component
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