Apple AppleScript Finder Guide - Manual (Page 149)

C H A P T E R 3
Finder Commands
Command Definitions
137
Update 3
An Update command is a request to update an object and its elements, if any,
to match their representation on disk. This involves making new items show
up in the correct position and updating the desktop database. The Finder
updates containers automatically when processing time is available; the
Update command just causes it to happen immediately.
SYNTAX
update referenceToObject
PARAMETERS
referenceToObject
A reference to the container or containers to update.
Class: Reference or list of references
RESULT
Reference to the updated container or a list of references.
EXAMPLE
tell application "Finder"
update {startup disk, disk "Data"}
end tell