The 法 (Ho) in 呼吸法 Kokyuho is commonly defined as "law," such as a "law of nature" or "Buddhist law."
Also, though in the Chinese reading (it differs little in this case) -- in 兵法 Bīng Fǎ, Sun-zi's famous treatise on war. 法 is closer in reference to the Greek techne
which we now separate into two aspects "art" and "technology" -- but they did not. And so our technology became ugly and our art useless.
There is a lesson here, I think.
Of course Aiki Age and Aiki Sage, on the surface at least, appear to be a bit more discrete in their directional reference than Kokyu . . . on the other hand, if they are not linear in nature then where does the Age or Sage begin or end exactly? Perhaps there specificity is more of a referent of relative convenience rather than an absolute.
I identify aiki with the manipulation (法?) of pure shears. Pure shears exploit the gyrational qualities of structures
, statically and dynamically. Juji
or the perpendicular principle of action, alters the eccentricity of loads on the structure, to create shears from existing poised loads without altering them directly.
A wave is a dynamic shear translated through a medium. In a wave, the water at the trough edge is drawn under and up the rear of the swell. The crest is drawn over and down the face. This is the principle/law/method of aiki age and aiki sage/inyoho/kokyuho etc...
If pure shear is present both complementary actions are in action simultaneously in every case -- but, as in the breaking wave (aiki sage) or the tsunami's lengthy drawout (aiki age) -- not always obviously coincident -- dare I say, one is quite often omote
and the other ura