Special values

Imported data tables may contain special values to signify absent, not recorded, trace or below detection limit values. For example, an assay value of -1 in the Ag field might signify "not recorded" and a value of -9 in the Fe field might signify "below detection limit".

To set conversions

Import the table.
Choose Data | Set Conversions display the Data Conversions dialog.
In the Column box, select the Table and Column name, or check the Apply to All Columns option.
In the Value box, type the special value you wish to convert in the Data Value box.
Type the value you wish to convert to in the Convert To box, or select one of the special value symbols by clicking the down arrow button:

Symbol	Value	Description
?	absent	Value unknown or not recorded
>0	trace	Small positive value
<	detection limit	Below measurement tolerance
-	bottom	Very large negative number
+	top	Very large positive number

Choose the Add button.
Repeat steps 3 to 6 for each value conversion required in each field in each table.
Choose OK to apply conversions.

The data conversions are saved in the document and applied to the imported tables whenever the document is opened.

	Related Topics
	Drillhole data validation