cov—country visited
lov—length of visit (days)
nov—number of visits including previous visits
ctz—citizenship
yov—year of visit
lps—language (other than mother tongue) with proficiency to speak
lpu—language with only proficiency to understand
hs—history was studied (1—yes, 0—no)
Typical entries may appear as noted in Table 16.1.
Table 16.1 Example Database
Nameagectzcovlovnovyovlpslpuhs
John Smith35U.S.India411994Hindi1
John Smith35U.S.Italy721991Italian1
John Smith35U.S.Japan3119930
When a query is made to list persons that visited India or Japan after 1992 for 3 or more days, John Smith’s
two entries will be included. The conditions stated for this query are straightforward, with lov [ge] 3 and yov
> 1992 and (cov = India or cov = Japan).
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