We can customize Forecast Category value from Forecast Category field in Opportunity object.
From above screenshot, Forecast Category value has been modified from Best Case to Best Case OK, but the Status Category will remain as Best Case.There are 5 Forecast Category values and we cannot add/delete it, although you can skip to use in from Stage assignment:
- Pipeline- Best Case
When you click Forecasts tab, you will find the 5 Forecast Category:
- Best Case
The Forecast Category on the Opportunity record do NOT maps directly on a one-to-one basis to the one on Forecast tab. Amount in Closed, Commit, Best Case, Pipeline is NOT total from the same Forecast Category in Opportunity Forecast Category. Click the Forecasts tab and notice that your forecast amounts are listed in different categories.
Forecasting Category value calculation:
Closed includes amounts for closed/won opportunities.
Status Category = Closed
Commit includes amounts you are confident about closing and closed/won opportunity amounts.
Status Category = Closed + Commit
Best Case includes amounts you are likely to close, closed/won opportunity amounts, and amounts in the Commit category.
Status Category = Closed + Commit + Best Case
Pipeline includes amounts from all open opportunities.
Status Category = Commit + Best Case + Pipeline
Sample of source data from Opportunity and relation with Forecast Category (bottom image):
See Salesforce.com documentation related to this.