Derivation
variable: dpthh1datex (table[s]: css_sei_all, gp_va, tmt_tmtv, ves_vese)
When variable is collected with DPT & HH together they are split:
foreach var in yn date datex vc {
forvalues x=1/3 {
gen dpt`x'`var'=dpthh`x'`var'
gen hh`x'`var'=dpthh`x'`var'
drop dpthh`x'`var'
}
}