5.1.1.1 Program structure

107 A C program need not all be translated at the same time.

108 The text of the program is kept in units called source files, (or preprocessing files) in this International Standard.

109 A source file together with all the headers and source files included via the preprocessing directive #include is known as a preprocessing translation unit.

110 After preprocessing, a preprocessing translation unit is called a translation unit.

111 Previously translated translation units may be preserved individually or in libraries.

112 The separate translation units of a program communicate by (for example) calls to functions whose identifiers have external linkage, manipulation of objects whose identifiers have external linkage, or manipulation of data files.

113 Translation units may be separately translated and then later linked to produce an executable program.

114 Forward references: linkages of identifiers (6.2.2), external definitions (6.9), preprocessing directives (6.10).