The ddcon command connects to a data source returning a connection handle, using the form:
[ch=. ddcon 'dsn=jdata' 1
We have now connected to a data source, but not yet to a data file. The file we will use is tdata, and the next statement uses ddcol to retrieve the column names and attributes for this file:
$cols=. 'tdata' ddcol ch
7 13
3 4 7 {"1 cols
+------+----+---------+
|Column|Type|Type_Name|
+------+----+---------+
|NAME |1 |CHAR |
+------+----+---------+
|SEX |1 |CHAR |
+------+----+---------+
|DEPT |1 |CHAR |
+------+----+---------+
...