Is STRING(MAX_CSV_FIELD_LENGTH) a kind of data?

I want read CSV data in twincat3. I used simple example of beckhoff to solve this.
there are some strenge line in global var such these:

{attribute 'Tc2GvlVarNames'}
VAR_GLOBAL CONSTANT
MAX_CSV_ROWS: UDINT := 6400;
MAX_CSV_COLUMNS: UDINT := 0;
MAX_CSV_FIELD_LENGTH : UDINT := 100;
END_VAR

there is another sentence on the code:
database: ARRAY[0..MAX_CSV_ROWS, 0..MAX_CSV_COLUMNS ] OF STRING(MAX_CSV_FIELD_LENGTH);

so what kind of database type is?
I used UDINT and STRING to solve but there is no effect at all. what should I do?

Those are constants. For example: Constant "MAX_CSV_ROWS"' defines maximum number of rows in your database which is declared as ARRAY [0..MAX_CSV_ROWS] OF STRING. So it means your array is ARRAY [0..6400] OF STRING

"MAX_CSV_FIELD_LENGTH" defines maximum number of characters in your string.

See also:
https://infosys.beckhoff.com/englis...1033/tc3_plc_intro/36028799548248203.html&id=