Model 40 Re: IBM 360 Model 50 information?

[Bill Degnan]

On Mon, Apr 1, 2019 at 8:59 PM Steve Malikoff via cctalk <
cctalk at classiccmp.org> wrote:

> Marc said
> > Which brings us to the real problem: we don’t have 360 Model 50 ALDs.
> Anyone has them?
> >
> > Marc
>
> And same for the Model 40 ALDs. All I have is one or two pages of the 2040
> ALD's and some peripheral ALD's only
> saved because I'd drawn artwork on the back, or they got used for book
> covering.
> I've not scanned them yet but should get to that sometime. Sadly there's
> not much there. A while ago I did scan a
> tiny fragment of the Model 40 development doc from Hursley
> https://archive.org/details/@galasphere347
>
> Steve.
>

What does ALD stand for?
Bill