CoM Energy

I just received an email from Ron Settles on the ILD optimisation list that included this:

---------------

--The optimum c.m.energy for doing Higgs measurements is
\sqrt{s}=m_Z+m_Higgs+ca.20GeV as has been pointed out many times recently
(and even during Lep days); I think most people have now changed to this
(the Snowmass05 energy was not optimum for m_Higgs=120GeV); it would be
best if all use the optimum energy to make comparisons/combinations
easier.

-----------------

I'm not sure what "ca" means? Does this agree with our CoM energy of 250?