Shimano Bantam 100ex

[Hytekrednek]

Can someone tell me what the on/off cast control switch on a blue Bantam 100EX is for or does exactly? It is on the left side plate opposite the handle side. It looks to be common that the switch comes out some how and gets lost. I see them for sale all the time and many of them are missing the switch.
I love the Bantam 100. I just got done rebuilding 2 of them with a new gear sets, ball bearings, and new carbon drag disc. I put an Avail lightweight/shallow spool on one of them. They both now look and function like new, actually better than new with the abec 7 bearings and carbon drag disc, plus a bushing in both was upgraded to a ball bearing.
I have one more to rebuild. My late father-in-laws Shimano 10XSG. In the middle of that project right now.

Thanks for any help or info on the switch on the bantam 100EX. I am just curious.

[Rancanfish]

Not familiar with that model, but on my Bantams it turns the anti-reverse of to allow back reeling.