User blog comment:Hyp cos/R function II/@comment-2033667-20150406074146/@comment-11227630-20150407090601

Nice. But I'm sorry I made a change just now.

Now we can have lbrace of a separator immediately after lbrace of a brace not separator. (e.g. nR{{0+1}1}) We cannot write a single separator at nested level = 1 now - at least there must be a number or a brace not separator immediately after it. (e.g. nR{0+1} is not valid but nR{0+1}1 is valid.) Just simplify a little.

Answer the question: things like nR00 are valid.

Though nR00 and nR{{0+1}1} are valid - they're valid in the definition. Those things fit the rules but are hard to read. We just scan pass some 0's so nR0000k is equivalent to nRk, nR{{0+1}1} is equivalent to nR{0{0+1}1}; and nRk1k2...kl is just equivalent to nR(k1+k2+...+kl).

Note: nR{0+1} is not valid now! It'll cause we scan nothing and the rules break! That's why I made this change.