Repeatable read isolation level and locks

I have two questions concerning repeatable read isolation level and row locks. 1. Why is a lock placed on the index value for the NEXT row after the one I select? Is there anyway around this? 2. I want my application to query sysmaster:syslocks (is there another way?) to inform the user that the row being viewed can not be updated. What is the significance (in detail) of the value of the keynum column and why is the type column null for locks held by my application? I'm sorry, that was really more than two questions, but answers (or pointers to references) to any of them will be greatly appreciated. Thanks, Jeff