Syntax for accessing deep roster's variable

Syntax
#1

Hi, if I have nested roster with depth of 3, i.e., Ro_depth1–>>Ro_depth2–>>Ro_depth3–>>my_question, can I access the inner variable using following syntax: Ro_depth1[idx].Ro_depth2[idx].Ro_depth3[idx].my_question? Thank you in advance.

#2

what is idx?
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#3

@sergiy I mean the index,e.g. 0 or 1, …

#4

Addressing like this is possible with the understanding that idx is a row code, NOT a row index.