How do you disable a unit completely without deleting it from the XML?

[Immortal Ace]

For RFC, I wanted to restrict my game to the Renaissance era. As in, even though I progress all the way down the tech tree, the game will still look as if I'm in the renaissance era and I could still build that era's units.

I'm having trouble with the units part. When I delete all industrial/modern/future units from the XML, for whatever reason, the game crashes around 1500-1600AD; I'm not sure why.

Is there any way to disable these said units from the XML without deleting their entry all together? I've been told to raise hammers so they do not get built; however, it's not an option for me.

If I simply raise the costs, units like Galley, Frigate, Ship of the Lines get obsolete by more modern units which I do not want. Modern units that no one can build because of setting the hammer cost to a ridiculously high amount.

I want to disable modern units from the XML so that Grenadiers, Cannons, Rifleman, Galleys, Frigates, Ship of the Lines, etc. never get obsolete so that I could build them throughout the game.

Can anyone help me on this?

 

[ClassicThunder]

I believe that if you set the cost to -1 then a unit in not trainable.

 

[Immortal Ace]

I believe that if you set the cost to -1 then a unit in not trainable.

Really?

I shall go try this.