Primary & Extended Partition

Reference: Case number: 1739966

Extended (or Logical) partitions are normally tagged to a Primary Partition but if I have 2 or more Primary, are the Logical Partition #1, 2, 3 4 tagged to the 1st Primary partition or can it be tagged to the 2nd or 3rd Primary Partition? 

I asked this because if the OS in the 1st Primary fails, will the other Logical partition be affected? Or can I create an Extended Partition under another Primary Partition.

Sorry, I am still new to this area, although I have partitioned more than 20-30 times over my past 30 years.

Thanks

Phillip

http://en.wikipedia.org/wiki/Disk_partitioning

this may help