IEC 60076-1 indicates:
7.1 Information to be given in all cases:
a) Kind of transformer (for example transformer, auto-transformer, booster transformer, etc.).
b) Number of this standard.
c) Manufacturer's name.
d) Manufacturer's serial number.
e) Year of manufacture.
f) Number of phases.
g) Rated power (in kVA or MVA). (For multi-winding transformers, the rated power of each winding should be given. The loading combinations should also be indicated unless the rated power of one of the windings is the sum of the rated powers of the other windings.)
h) Rated frequency (in Hz).
i) Rated voltages (in V or kV) and tapping range.
j) Rated currents (in A or kA).
k) Connection symbol.
l) Short-circuit impedance, measured value in percentage.
m) Type of cooling. (If the transformer has several assigned cooling methods, the respective power values may be expressed as percentages of rated power, for example ONAN/ONAF 70/100 %.)
n) Total mass.
o) Mass of insulating oil.
7.2 Additional information to be given when applicable ... depend on transformer type and accessories