//

The two /|slashes // may indicate:
 * a comment in several programming languages including C, C++ and Java
 * the root directory path in Domain/OS
 * the operator for integer division in Python 2.2+
 * the empty pattern in Perl, which evaluates the last successfully matched regular expression
 * the logical defined-or operator in Perl, called the null coalescing operator in other programming languages
 * the authority indicator in the URI scheme
 * the descendant-or-self axis specifier in XPath