The DECset Environment Manager for OpenVMS provides a single
    mechanism for tailoring the execution environment for a set of
    DECset tools. The tailoring factor is known simply as a context.

    Using the DECwindows user interface, a context may be applied
    to all tools displaying on a particular DECwindows display.
    Using the command line interface, a context may be applied to
    a particular process and all subprocesses subsequently created by
    that process.

    Context
    A context is defined as a named set of values that tailors the
    DECset tools to a specific software development activity (for
    example, fixing bugs or implementing enhancements). The supported
    attributes for which these values are supplied are: logical name
    definitions; symbol definitions; MMS macro definitions; MMS build
    options; linker options file specifications; library settings; a
    source directory specification; output directory specifications;
    and a default directory specification.

    Each context has a unique name. The context name is limited to
    a length of 16 characters. There can be only one context in a
    particular context database with that name.

    At any given time, the named context most recently applied to a
    tool is known as the tool's current context. If no context has
    been applied, the tool has no current context.

    A tool's execution environment is not fully defined by the values
    associated with a named context. Rather, a tool's execution
    environment is constructed from the following sources:

    1. the parent process

    2. the X Windows resource file (if applicable)

    3. the named context (if applicable)

    4. the command line qualifiers used to invoke the tool

    A specification retrieved from a higher-numbered source always
    supersedes any specification of the same object retrieved from a
    lower-numbered source.

    Context Hierarchy
    A project context is one that is associated with a development
    project. A project context is typically used by all persons
    working on the particular project.

    A user-specific context may be based upon a project context,
    thereby tailoring the project context to a particular user. In
    this case, the project context becomes a parent context.

    A context that is based upon another context is said to be a
    child context. Each child context inherits all the information
    associated with its parent context. If the same attribute in both
    a child and its parent have different values, the child's value
    overrides that of the parent.

    Any context may be based upon another context, which (in turn)
    may itself be based upon yet another context. A child context
    inherits information from its entire `chain' of parent contexts.
    The term context object refers to a context that includes all of
    this inherited information.

    Context File
    A context file is used to store information that is specific
    to a particular named context. The context file is specified by
    an OpenVMS file specification, which is stored in the context
    database entry associated with the named context.  The default
    context file type is .DECSET_CONTEXT.

    The context file is a sequential ASCII text file. In a context
    file, a continuation line must be terminated by a hyphen
    character. Trailing comments are not allowed on a continuation
    line. The context file specification must exist in the format:
    disk:[directory.subdirectory]*.decset_context. If you specify a
    node name in the File menu New Context... Context File field-
    even if the node name is part of a local cluster-the node
    specification is invalid at the time of context file retrieval
    from the context database.

    Context Database
    A context is defined in a context database. This database is
    stored as a sequential ASCII text file. Each record of this file
    has the following format:

      context-name  context-file-spec  [parent-context]  ["context-description"]

    A context database entry must include a complete file
    specification; for example, DISK12:[USER.DIRECTORY]context_
    database_file.DECSET_CONTEXT_DB.

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