Highlighting Date Range Where a Condition From Another Cell is Not Met

[gbc123]

Hi Folks,

I hope you can assist me. I've tried a few IF, AND combinations and even Pivots without success hence the plea.

I am looking to determine, per Reference, any date range for that reference that is not covered by a period where the Main Position = 1.

Reference Date From Date To Main Position

1001 01/01/2015 05/08/2018 1
1001 01/01/2015 11/11/2018 0
1001 06/08/2018 31/12/2099 0 Expected result for 1001 to tell me the period 06/08/2018 to 31/12/2099 has no Main Position = 1 entry.

1002 10/10/2017 10/10/2018 1
1002 05/12/2016 31/12/2020 0 Expected result for 1002 to tell me the periods 05/12/2016 to 10/10/2017 AND 10/10/2018 to 31/12/2020 have no Main Position = 1 entries.

Also, where would the formula go?

Appreciate the forum's help in advance.

Thanks.

Gary.