by the United States Department of Defense

“ It shall be possible in programs to define more than one physical representation (e.g., packed and unpacked) for elements of a given type, and to associate a specific representation with each variable of that type. [Note that changes of representation can be accomplished through assignment.] ”

“ A value accessing operation shall be automatically defined for each component of composite data elements. Assignment shall be automatically defined for components that have alterable values. A constructor operation (i.e., an operation that constructs an element of a type from its constituent parts) shall be automatically defined for each composite type. An assignable component may be used anywhere in a program that a variable of the component's type is permitted. ”

“ Translators shall be responsible for reporting errors that are detectable at translation time and for optimizing object code. Translators shall do full syntax and type checking, shall check that all language imposed restrictions are met, and should provide warnings of unusually expensive constructs. A representative set of translation time diagnostic and warning messages shall be included in the language definition. ”

“ It shall be possible to associate identifiers with constant values of any type that is not dynamically allocated. Constants shall include both those whose values are determined at translation time and those whose value cannot be determined until scope entry time. ”

“ The range of each integer and fixed point variable must be specified in programs and determinable at translation time. Such specifications shall be interpreted as the minimum range to be implemented. Explicit conversion operations shall not be required between numeric ranges. ”

“ The type of each variable, array and record component, expression, function, and parameter shall be determinable during translation.
3B. IMPLICIT TYPE CONVERSIONS
There shall be no implicit conversions between types.
3C. TYPE DEFINITIONS
It shall be possible to define new data types in programs. Type definitions shall be processed entirely at translation time. The scope of a type definition shall be determinable at translation time. No restriction shall be imposed on defined types unless it is imposed on all types. ”

“ Translators shall fail to compile correct programs only when the program exceeds the resources or capabilities of the intended object machine or when the program requires more resources during the translation than are unavailable on the host machine. Translators shall report an error when a program requires memory, devices, or special hardware that are unavailable in the object machine. ”

“ Where possible, features should be chosen to have a simple and efficient implementation in many object machines, to avoid execution costs for available generality where it is not needed, to maximize the number of safe optimizations available to translators, and to ensure that unused and constant portions of programs will not add to execution costs. ”

“ An encapsulation may contain definitions of the data elements comprising a type and of operations.
3-5B. EFFECTS OF ENCAPSULATION
The effect of encapsulation shall be to inhibit external access to implementation properties of the definition. In particular declarations made within an encapsulation shall not automatically be accessible outside the encapsulation. Data elements defined in an encapsulation shall not automatically inherit the operations of the types with which they are represented. ”

“ During specified portions of its execution, a parallel path shall be able to wait for and gain exclusive use of certain program declared objects and to release those objects. [Note that special asynchronous hardware and software interrupt facilities are not necessary in the language; interrupts can be treated as objects that are released upon occurrence of the interrupt.]
9D. REAL TIME CONSTRAINTS AND SCHEDULING
Constraints on the real (i.e., elapsed) time for execution of portions of control paths shall be specifiable in programs. ”

“ This revision does not alter the basic intent or substance of the December 1975 The revised requirements are hierarchically organized with an outline similar to that expected in a language defining document. Section l gives the general design criteria. These provide the major goals that influenced the selection of specific requirements and provide a basis for language design decisions that are not otherwise dealt with in the requirements. ”

“ Aliasing (i.e., multiple access paths to the same variable from a given scope) shall not be permitted. In particular, a variable may not be used as two output arguments in the same call to a procedure, and a nonlocal variable that is accessed or assigned within a procedure body may not be used as an output argument to that procedure.
8. INPUT-OUTPUT FACILITIES 8A. LOW LEVEL INPUT-OUTPUT OPERATIONS
There shall be a set of built-in low level input-output operations that act on physical files (e.g., input-output channels and peripheral devices) . ”