Registration

Information on DOS settings is stored in a "database" in the operating system kernel. This database is used to support all operations related to DOS settings. The following information is registered for each setting:

Name

The name presented to the user. This may contain blanks, and related settings should have common prefixes so that they sort together in the list presented to the user (such as Printer buffer size, Printer timeout, Printer automatic close).

For the "standard" settings, specific ordinals are used so that the kernel may obtain the value independently of the name string.

The name of the help file containing help information on this setting.

The help ID of the main topic for this setting.

The setting type. The following types are supported:

Boolean

Integer

Enumeration (list of valid strings)

Single-line strings

Multi-line strings.

This allows the user interface to display an appropriate control for each setting.

Flags
These control aspects of the setting. In particular, the flags determine whether the setting can be changed while a VDM is running.
Default Value
If the user does not supply a value, this default value is used.
Validation information
This information allows the user interface (and the kernel) to validate settings without involvement from the virtual device driver. For strings, this is the maximum string length. For integers, this is the minimum, maximum, and step values. For enumerations, this is the list of valid strings.
Function
This function is used for validating string settings, and for notifying the VDD when the user has changed a setting value for a running VDM.

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