Data import - no wind

[riteoh]

I know I've found the answer to this question somewhere before - but for the life of me, can't find it now.

Due to my station going offline due to my Cron Job failing, I have to manually upload the data for that period.

When importing the data, what do I use when there has been no wind for that period? It seems that a direction of North is registered as 0 - so can't use that. Do I just leave the field blank?

Thanks.