frames = FrameSystem{4, Float64}()       # Order 4 (through jerk), Float64, TDB timescale
frames = FrameSystem{2, Float64, TDB}()  # Explicit timescale

# Celestial/Inertial
add_axes_icrf!(frames)
add_axes_gcrf!(frames)
add_axes_eme2000!(frames)

# Terrestrial (IERS)
add_axes_itrf!(frames, iers2010b)
add_axes_cirf!(frames, iers2010b)
add_axes_mod!(frames, iers2010b)
add_axes_tod!(frames, iers2010b)
add_axes_pef!(frames, iers2010b)

# Planetary / Lunar
add_axes_bci2000!(frames, body)
add_axes_pa440!(frames)          # Moon principal axes DE440
add_axes_me421!(frames)          # Moon mean Earth DE421

add_axes_fixedoffset!(frames, :MyFrame, id, parent_id, dcm)
add_axes_rotating!(frames, :MyFrame, id, parent_id, fun, δfun, δ²fun, δ³fun)
add_point_fixedoffset!(frames, :MyPoint, id, parent_id, axes_id, offset)
add_point_dynamical!(frames, :MyPoint, id, parent_id, axes_id, fun)
add_point_ephemeris!(frames, eph, ...)

r    = vector3(frames, from, to, axes, epoch)     # SVector{3}  position
rv   = vector6(frames, from, to, axes, epoch)     # SVector{6}  pos + vel
rva  = vector9(frames, from, to, axes, epoch)     # SVector{9}  pos + vel + acc
rvaj = vector12(frames, from, to, axes, epoch)    # SVector{12} pos + vel + acc + jerk

R  = rotation3(frames, from, to, epoch)    # Rotation{1} (DCM only)
R  = rotation6(frames, from, to, epoch)    # Rotation{2} (DCM + dDCM/dt)
R  = rotation9(frames, from, to, epoch)    # Rotation{3}
R  = rotation12(frames, from, to, epoch)   # Rotation{4}