-Consider four categories B,C,D, and E.
-Let F be a functor from B to C; G,H, and J be functors from C to D; and K and L be functors from D to E. Let eta be a natural transformation from G to H; phi be a natural transformation from H to J; and psi be a natural transformation from K to L. Pictorally:
+Consider four categories `B`, `C`, `D`, and `E`. Let `F` be a functor from `B` to `C`; `G`, `H`, and `J` be functors from `C` to `D`; and `K` and `L` be functors from `D` to `E`. Let `eta` be a natural transformation from `G` to `H`; `phi` be a natural transformation from `H` to `J`; and `psi` be a natural transformation from `K` to `L`. Pictorally:
+
+ - B -+ +--- C --+ +---- D -----+ +-- E --
+ | | | | | |
+ F: ------> G: ------> K: ------>
+ | | | | | eta | | | psi
+ | | | | v | | v
+ | | H: ------> L: ------>
+ | | | | | phi | |
+ | | | | v | |
+ | | J: ------> | |
+ -----+ +--------+ +------------+ +-------