Grammar in chapter 4

[denniskb]

188: ... Lines 13 to 23 all in one block marked (1). ...

should be “Lines 13 to 23 are all in one block marked (1).”?

188: ... Line 23 is the only line in another block in a block marked as (3). ...

Is this correct? Possibly rephrase “in another block in a block” as it's a bit confusing.