Full Generic System V ABI

t i m e _ t _ a l t z o n e ;This variable contains the difference, in seconds, between UniversalCoordinated Time and the alternate time zone, as establishedwith the function t z s e t.u n s i g n e d c h a r _ n u m e r i c [ 2 ];This array holds local-specific information, as established by thefunction s e t l o c a l e . Specifically, _ n u m e r i c [ 0 ] holds thedecimal-point character, and _ n u m e r i c [ 1 ] holds the characterused to separate groups of digits to the left of the decimal-pointcharacter in formatted non-monetary quantities. See the functionl o c a l e c o n v for more information.XXXApplication ConstraintsAs described above, l i b s y s provides symbols for applications. In a few cases,however, an application is obliged to provide symbols for the library.e x t e r n c h a r ** e n v i r o n;Normally, this symbol is synonymous with e n v i r o n, as the functione x e c describes. This isn’t always true, though, because ANSI C doesnot define e n v i r o n. Thus, an ANSI C-conforming application candefine its own e n v i r o n symbol, unrelated to the process environment.If the application defines e n v i r o n and intends it to have theX/Open CAE Specification, Issue 4.2 and the System V InterfaceDefinition, Third Edition semantics, it must also define _ e n v i r o n sothat the two symbols refer to the same data object.XXSystem Service SynonymsIn addition to the routine names listed in the tables above, the system libraryincludes synonyms for some of its services. These other symbols are available toconform to language and system standards. As an example, System V definesr e a d as the name of an operating system facility. On the other hand, ANSI C doesnot define r e a d, and it prohibits a strictly conforming implementation from usurpingapplication names without a leading underscore ( _ ). Thus if a synonym forr e a d were not available, the system could not support a strictly conformingimplementation of the ANSI C language.name This gives the traditional name, such as r e a d.6-8 LIBRARIES