meso structures

in polymers
https://doi.org/10.1351/goldbook.M03856
Relative configurations of consecutive, but not necessarily contiguous, constitutionally equivalent carbon atoms that have a symmetrically-constituted connecting group (if any) are designated '@M03838@' or 'racemo', as appropriate. Examples:
M03856-1.png
(The symbol M03856-2.png represents a symmetrically-constituted connecting group, such as –CH2, –CH2–CH2, or –CR2–CH2–CR2.)
Source:
Purple Book, 1st ed., p. 37 [Terms]