I'm hoping someone here can recall when the button tool was first introduced to InDesign. I'm pretty sure it was new to version 3 (CS), but wanted to confirm. (For those who may be wondering where it is nowadays, it was replaced with a different method of creating buttons with version 6/CS4.)
I also have a question about creating interactive buttons in version 3, specifically how long a button name could be. With versions 4 and 5 (CS2, CS3), the UI allowed names in excess of 200 characters. This was reduced to a maximum of 32 characters with versions 6, 7, and 7.5, and increased to a maximum of 100 characters for subsequent versions. So if anyone happens to be able to easily test ID CS to see how many characters it allows, I'd appreciate it. This isn't for anything too important, just historical accuracy in some materials I'm preparing, so spending hours finding and firing up that old laptop hiding in the basement isn't allowed.
There were definitely no buttons in InDesign 2.
Here's the best source on what features were available in earlier versions of InDesign, designed by James Wamser:
Thank you Steve. That's a useful resource.