The OpenVMS Run-Time Library (RTL) is a library of prewritten, commonly used routines that perform a wide variety of functions. These routines are grouped according to the types of tasks they perform, and each group has a prefix that identifies those routines as members of a particular OpenVMS RTL facility. Table 3-10 lists all the language- independent, run-time library facility prefixes and the types of tasks each facility performs.
| Facility Prefix | Types of Tasks Performed |
|---|---|
| DTK$ | DECtalk routines that are used to control the Digital DECtalk device. |
| LIB$ | Library routines that obtain records from devices, manipulate strings, convert data types for I/O, allocate resources, obtain system information, signal exceptions, establish condition handlers, enable detection of hardware exceptions, and process cross-reference data. |
| MTH$ | Mathematics routines that perform arithmetic, algebraic, and trigonometric calculations. |
| OTS$ | General- purpose routines that perform tasks such as data-type conversions as part of a compiler's generated code. |
| SMG$ | Screen management routines that are used in designing, composing, and keeping track of complex images on a video screen. |
| STR$ | String manipulation routines that perform such tasks as searching for substrings, concatenating strings, and prefixing and appending strings. |