Why does resource ID start from 3 rather than 2?

Chapter 23.10 of Writing with Inform says:

In the released, blorbed-up Glulx file, figures and sound effects are internally given resource ID numbers which count upwards from 2 in order of their declaration. (Figure and sound numbers can thus be intermingled, if their declarations are.) Resource ID number 1 is reserved for the image of the cover art, if there is any.

In my projects, the resource ID numbers start from 3.

Is this a sign that something is wrong?

I have sounds (declared like Sound of Z is the file "Z.ogg".) but no images or other files.

Thank you.

It does appear to be normal to have ID 2 skipped in the numbering, but I don’t know why.

Perhaps it’s reserved for the small cover image (which currently is not included in the blorb file)?

(I had a look at the internal content of a blorb from a story that contains only images, and ID 2 was simply never used.)

Thank you. That is enough to set my mind at rest.

Typically you shouldn’t have to care about the specific resource IDs that get assigned to any one thing. Within your source text you should only use the name to refer to a resource (since they can get renumbered if you move source around).

You do have to partly care about them when working with Parchment, but mostly only to the extent of getting a tool to automatically generate the resource map for you.

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