North London line then it was switched to . Later, it was cut back to . A tunnel, the Hampstead Heath tunnel, runs under Hampstead between and . The line is double track throughout, with a mix of triple and quadruple track between and . The former North Woolwich branch included a section of single track between Custom House and North Woolwich stations, and the Broad Street branch was at one time formed of quadruple track. During the February–May 2010 blockade, the , and stations were rebuilt to allow the extended East London line to serve Highbury & Islington on fully segregated tracks
Quadruple-precision floating-point format switch) or simply as being synonymous with double precision (e.g. Microsoft Visual C++), rather than as quadruple precision. On a few other architectures, some C/C++ compilers implement codice_8 as quadruple precision, e.g. gcc on PowerPC (as double-double) and SPARC, or the Sun Studio compilers on SPARC. Even if codice_8 is not quadruple precision, however, some C/C++ compilers provide a nonstandard quadruple-precision type as an extension. For example, gcc provides a quadruple-precision type called codice_14 for x86, x86-64 and Itanium CPUs, and on PowerPC as IEEE 128-bit floating-point using the -mfloat128-hardware or -mfloat128 options; and some versions of Intel's C/C++ compiler