A text-delimited file, passed to fread from data.table.
Value
A data.table with column names in ascending (lexicographical) order and
any columns starting with e will be uppercase.
Details
The strings "" "NA" "?" "." "*" "**" are treated as missing, as well as ZZZZZZZZZZ
(so students without a CHESSN will be marked with the integer64 missing value).