Hi Nelly,
For this indicator the denominator/unit of analysis is nets. While you could probably calculate it without having to reshape the dataset, reshaping helps get the unit of analysis to be ITNs.

Here is an example of calculating this indicator using Uganda 2014-15 MIS data.

use "UGHR72FL.DTA", clear

*Weighting the data
gen wt=hv005/1000000

*Reshaping the dataset to a long format
reshape long hml10_ hml21_ ,i(hhid) j(idx)

gen sleepnet=0
replace sleepnet=1 if hml21_==1

gen ownnet=0
replace ownnet=1 if hml10_==1

tab sleepnet if ownnet==1 [iweight=wt]