Using ' ' (single quotes) as field values

Hello,

Please can anyone let me know what is the purpose of using ' ' (single quotes) as field values used especially for Org element fields along with the actual values in R/3. For eg. I have seen cases where in you have the value for field WERKS as ' ' plus say 1000. I have also seen cases in the past (dont distinctly remember) where the authorizations failed when the single quotes got removed.