All items in this auction are authentic unless it says "Reproduction" or "Fantasy" in the title or description.
Reproduction is a exact copy of the original item
Fantasy item was never original used by the company, it may have been a magazine ad or such, but was never a sign, globe or etc.
Tin over cardboard is a metal sign wrapped on a cardboard back

SST - Single Sided Tin 
DST - Double Sided Tin
DSP - Double Sided Porcelain 
SSP - Single Sided Porcelain 
And so on and so forth for any abbreviations 

Reach out with any questions