as explained in the following comment by @t6s https://github.com/math-comp/analysis/pull/1868#pullrequestreview-3880114483 and completed by the notation proposed by @CohenCyril in this other comment https://github.com/math-comp/analysis/pull/1868#issuecomment-3991014841
as explained in the following comment by @t6s
#1868 (review)
and completed by the notation proposed by @CohenCyril in this other comment
#1868 (comment)