Time Based weighting factors in time stream id

Dear Expert,

I read this

If the key figure values prior to distribution were initial, and if a time stream ID forms part of the storage buckets profile definition, the system checks to see if time-based weighting factors exist for this time stream

In this SAP help link

Aggregation and Disaggregation - Interactive Demand Planning - SAP Library

What are these time based weighting factors of a time stream? Where are these weighting factors defined ?. I do not see one in time stream ID period definition. Is is just the length of the time period in time stream ?

Thanks

BS