AppleScript: The Definitive Guide, 2nd Edition

Operations on Multiple References

When an element specifier would return a list of references, it may be possible to ask for an attribute of this list as a shorthand for asking for that attribute of each element of the list in turn; the request to fetch the attribute is applied distributively to each item of the list.

For example, this works, and returns a list of strings, the names of each disk in turn:

tell application "Finder" to get name of every disk

Similarly:

tell application "iTunes"
    tell view of browser window 1
        get name of every track
    end tell
end tell

Possibly you can even apply this construct to the result of a boolean test:

tell application "iTunes"
    tell view of browser window 1
        get database ID of every track whose name contains "Palestrina"
    end tell
end tell

Those examples illustrate a property; the same thing may work for an element:

tell application "Finder"
    get file 1 of every folder
end tell

When you request multiple elements distributed across a list in this way, whether you get back a list of lists or a single flattened list depends upon the individual application. For example:

tell application "Address Book"
    get every email of every person
end tell

The result of that code is a list of lists—the outer list has as many items as there are persons, with each item being a list of every email address of the corresponding person. But when you try something similar in the Finder, the result is a single list of files:

tell application "Finder" get every file of every folder end ...