URL "key" references.

Hello,

When viewing opportunity summary page the following link is produced:

http://pc-testing/CRM-TechDemo/eware.dll/Do?SID=76870168542691&Act=162&Mode=40&CLk=T&Key0=86&Key1=47&Key2=61&Key4=1&Key7=470&Key58=785&Key86=792

What entity/table is key0 referring to?