bisecting conformation (eclipsing conformation)

https://doi.org/10.1351/goldbook.B00673
For a structure containing the grouping R3C–C(Y)=X (with identical or different groups R) the @C01258@ in which the @T06406@ is such that X is @A00402@ to one of the groups R , and, in a @N04134@, the double bond C=X bisects one of the R–C–R angles. In this @C01258@ the bond C–Y@E01884@ one of the C–R bonds. The other @C01258@, in which X is @S06231@ to one of the groups R, is called an @E01885@.
B00673.png
Source:
PAC, 1996, 68, 2193. (Basic terminology of stereochemistry (IUPAC Recommendations 1996)) on page 2201 [Terms] [Paper]