My point however is that
the Thais themselves often don't refer to it as an extension but as a renewal, and even more confusing as
a renewal of extension, once there has been an initial extension. Or take this statement from a
supposedly reputable visa agent -
"Currently, you can apply to renew your visa 45 days before it expires. You should renew as early as possible and not leave it to the last minute." That's on the same page where they describe it as an extension. You can find multiple examples of this confusion on many sites serving the immigration needs of foreigners
To revert to my original point: - use technical terms, as paborn does, and assume that outsiders will understand them the way insiders do is a recipe for confusion