Environment Table

[This is preliminary documentation and subject to change.]

The Environment table is used to set the values of environment variables.

The Environment table has the following columns.

Columns

Environment

This is the primary key of the table and is a non-localized token.

Name

This column is the name of the environment variable. The key values will be written or removed depending upon which of the characters in the following table are prefixed to the name.

Prefix	Meaning
=	The name/value is to be created when installed.
+	The name/value is to be created, if absent, when installed.
-	The name/value is to be deleted, if present, when the component is uninstalled.
=-	The value is set on install and removed on uninstall. This is the usual behavior.
=+	This is not a valid prefix
*	The name refers to a system environment variable and by default the value will be written to the user's environment. This prefix is used with Windows NT.

If the Value field in the table includes a [~], then the prefix characters apply to only the specified portion of the string. The use of [~] is described below in the Value column section.

The environment variable is removed if the Value field of the table is blank. Therefore, with a blank in the Value field, an [=] prefix deletes the environment variable on install and a [-] prefix deletes any current values on uninstall.

Value

This column contains the value that is to be set as a formatted string. The contents of this field are modified as follows by using the character [~].

If [~] precedes the string, then the string will be attached at the end of the existing value.

If [~] follows the end of the string, then the string will be inserted at the beginning of the existing value.

If no [~] is present, then the string represents the entire value to be set or deleted.

If the Value field is blank, then the variable will be removed.

The character adjacent to the [~] in a preceding or appending value acts as a delimiter and separates one value from the next. For example, to add a value to the end of a semi-colon delimited list use "[~];new value".

Component_

External key to column one of the Component table. This column specifies the component whose key file provides the extension server.