Thanks for the speedy responses.
If these are custom made, there may be an ERS (Engineering Requirements Specification), or similar, that informed the vendor about what to build. Barring that...
The individual windings identified (e.g., transformer has three windings, around a common core)
Number of turns, each winding
Inductances and DR resistances for each winding (L, in henries and R in ohms)
Leakage inductance
The magnetic coupling between windings (K in unit-less fraction where 1 is perfect coupling and 0 is no coupling at all).
Parasitic capacitances (in farads)
Core type identified (e.g. E-I or toroidal).
Image, attached.
Thank you
Vince