Sagitta and sextupole field in dipoles

[Max]

I am trying to compute the tune shift due to the sagitta in a rectangular dipole with a sextupole field.
I am not sure whether Elegant computes the feed-down of the sexupole (or higher multipoles) that,
because of the sagitta, give rise to a quadrupole effect and a tune shift. In other words: is K2 defined (in RBEN)
with respect to the reference orbit or with respect to the dipole axis ?
cheers and thanks in advance, Max

[michael_borland]

Max,

K2 and all other multipoles are described with respect to the reference orbit. Put another way, it is implicitly assumed that the magnet is curved to follow the beam trajectory.

--Michael