$SControl

A global merge field type to use when referencing an existing custom s-control by name. This merge field type results in a URL to a page where the s-control executes.

Visualforce pages supersede s-controls. Organizations that haven’t previously used s-controls can’t create them. Existing s-controls are unaffected and can still be edited.

Use dot notation to access an existing s-control by its name.

The following example shows how to link to an s-control named HelloWorld in a Visualforce page:

Note that if you simply want to embed an s-control in a page, you can use the <apex:scontrol> tag without the $SControl merge field. For example: