New Post: Back-Button Ressource File?

Sorry for the (maybe silly?) question but I really can not find the resource file where I can translate the "Back" Button-Text in the checkout-Module...

I have searched through the resx (checkout.resx too) files and also examined the source of the checkout.ascx file where it is referenced as "cmdBack" ... but this key I was not able to find in the resourcefile for this control...

Any helpis highly appreciated
Thanks and regards
Don

NB Store 2.3.5