What should I enter as the sales category if Box 5 shows non-covered securities - code X (unknown holding period) on my 1099B form?

[ElenaV]

I entered the proceeds and the cost basis which is blank on the form, but I knew what I paid when I purchased the stock through my employee stock purchasing program.  .  

[DDollar]

For sales category, if you held it more than a year, indicate Box E - Long term non-covered.  If you held it less than a year, enter Box B -Short term non-covered.