whatever the highest index value that has data. If you say it holds 811 pieces of data, indexes are zero-based meaning 0 to 810 = 811
dbp help:
SAVE ARRAY
This command will save the contents of the array to the specified file. It is highly recommended that the
array used to save the data should be identical to the one used when reloading. When specifying the array
name, the array index numbers are ignored, but you must still provide them to ensure the array is
recognized.
SYNTAX
SAVE ARRAY Filename, Array Name(0)
-RUST-