These are not actual extensions. They are part of the PHP core and cannot be left out of a PHP binary with compilation options.
These extensions are bundled with PHP.
Henvisning VII, BCMath Arbitrary Precision Mathematics Functions
Henvisning XXIV, Database (dbm-style) Abstraction Layer Functions
Henvisning CXX, Regular Expression Functions (Perl-Compatible)
Henvisning XCIII, Microsoft SQL Server and Sybase Functions (PDO_DBLIB)
Henvisning XLIII, Firebird/Interbase Functions (PDO_FIREBIRD)
Henvisning CXLVI, Semaphore, Shared Memory and IPC Functions
In order to compile these extensions, external libraries will be needed.
These extensions are available from PECL. More PECL extensions exist but they are not documented in the PHP manual yet.