Missing enemy numbers in editor?

I don't know if this is already explained anywhere, but I've done several searches on it and didn't find anything, nor does the wiki seem to answer it...

Being extremely OCD, a long time ago I combed through the entire list in the enemy editor and took note of each enemy's number, and I noticed there appear to be many gaps in the order. By this I mean a large chunk of enemy numbers don't have actual enemies associated with them, and as such, don't even show up in the list. The most notable example is that Enemies 1 through 19 are missing. In total, there are 56 numbers missing out of the first 176. The unused numbers at the end of the list (e177 - e511) don't seem to have any gaps. Despite this, none of the enemies that exist in Zelda Classic are missing.

Recently I checked again and these gaps still exist. So, I still find myself wondering: are these missing entries used by various internal things that shouldn't be messed with, such as enemy types? Are they deleted entries that never returned for reuse? Or is it something else?

1-19 are guys, though not all of them are used. Higher numbers are dummied out. Additional enemies were planned at some point, but they were never finished, and their slots weren't made available again for whatever reason.