does it show up under "other record fields" in the drop down list @ericbirdsall

It does not 😕

Internal Id	Text
-112	Account
-289	Address
-242	Bin
-4021	Bonus
-107	Campaign Event
-117	Company
-108	Competitor
-101	Department
-438	Domain
-126	Expense Category
-553	Format Profile
-902	Imported Employee Expense
-246	Item Demand Plan
-506	Item Location Configuration
-425	Item Source
-247	Item Supply Plan
-355	Job
-103	Location
-294	Manufacturing Cost Template
-288	Manufacturing Routing
-303	Note
-102	Operations Center
-304	Payroll Batch
-265	Payroll Item
-118	Role
-522	Supply Chain Snapshot
-901	Supply Chain Snapshot Simulation
-128	Tax Code
-198	Tax Type
-386	Time-Off Change
-382	Time-Off Plan
-376	Time-Off Request
-383	Time-Off Rule
-377	Time-Off Type
-292	Timesheet
-129	Workflow
-196	Workplace

It's not a timesheet record?

No, it's sort of a subrecord of the timesheet record. Timesheet shows all times from a week. The timebill is a single entry of that timesheet

well makes sense, its sort of a subrecord, that would make it a transaction line

I suppose - just feels weird because its a "free standing" form. But now that I know, I should remember in the future