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# Material Class Cutoffs

You define material class cutoffs when you want to reclassify material part way through the schedule, for example because of a change in commodity prices or a change at your processing plant. Defining material class cutoffs is optional.

When you define material class cutoffs, the material class assignments replace the value for the material classes defined by the material class attribute.

Notes:

- The replacement of values for the material class attribute is in the working memory only when the schedule is run. The values in the material class attribute of the block model are not overwritten.
- You must redefine material classes so that all blocks are captured by the new definitions. For example, if you redefine your ore to have a higher value for the lower limit, you must also define your waste to have a higher upper limit so that the blocks that are no longer assigned to ore are now assigned to waste.
- You cannot apply material class cutoffs to the material classes if the material class attribute is a calculated attribute.

You set material class cutoffs in the Material Class Assignment spreadsheet. To access the spreadsheet view, select Spreadsheet > Enable Spreadsheet View, and then select the Material Class Cutoffs spreadsheet.

When the Material Class Assignment spreadsheet is enabled, a new Cutoffs tab appears at the bottom left corner of the 2D Canvas. When you select the Cutoffs tab, the Material Class Assignment spreadsheet replaces the 2D Canvas. To return to the 2D Canvas, click the Canvas tab.

### Columns in the Material Class Assignment Spreadsheet

Column | Description
--- | ---
Active? | Yes: The material class cutoff is active. No: The material class cutoff is inactive. Note: When you select no in the Active column, the material class cutoff is not used in the schedule. The Active setting allows you to maintain a history of cutoffs or to experiment with different cutoff settings without overwriting previous definitions.
Mining Location Names | The mining location or locations to which the material class cutoffs apply. Tip: You can use wildcards to specify more than one mining location. To specify the mining locations using the Wildcard Expression Builder, click the Ellipsis button.
Material Class Name | The material class that is being reassigned. You must select a material class that is defined in the Material classes data grid.
Quality Attribute Name | The attribute in the block model that determines the new cutoff values. This attribute is usually the quality, defined in the Qualities data grid, that you consider is the most important quality for your schedule.
Minimum Value (>=) | The minimum value for the attribute for the specified material class. Blocks that have a value for the attribute that is below this value are not assigned to this material class.
Maximum Value (<) | The maximum value for the attribute for the specified material class. Blocks that have a value for the attribute that is above this value are not assigned to this material class.
Effective Date | The date that the new material class cutoffs take effect. The date must be entered in DD/MM/YYYY format. If you leave this column blank, the material class cutoff is applied from the start of the schedule.
#1 Constraining Attribute Name | The first constraint that defines the material class. For example, the material class could be dependent upon the primary grade being greater than a cutoff value and a contaminant grade being less than a cutoff value. Note: All constraints are optional.
#1 Constraining Operator | The relationship between the attribute and value that must be satisfied by the block, for the block to be included in the material class. Options are: = : equal to > : greater than < : less than >= : greater than or equal to <= : less than or equal to
#1 Constraining Value | The value that the attribute must be equal to, greater than, greater than, less than, or less than or equal to, depending on the operator, for the block to be included in the material class.
#2 Constraining Attribute Name | The second constraint that defines the material class. For example, the material class could be dependent upon the primary grade being greater than a cutoff value, a contaminant grade being less than a cutoff value, and the material being a particular rock type. Note: All constraints are optional.
#2 Constraining Operator | The relationship between the attribute and value that must be satisfied by the block, for the block to be included in the material class. Options are: = : equal to > : greater than < : less than >= : greater than or equal to <= : less than or equal to
#2 Constraining Value | The value that the attribute must be equal to, greater than, greater than or equal to, less than, or less than or equal to, depending on the operator, for the block to be included in the material class.
Additional Constraint File | The constraints file that contains additional constraints that define the material class. To use more than two additional constraints, or to use constraints based on geometry, you must create a constraint file in GEOVIA Surpac and reference the file in this column. Note: All constraints are optional.
Comments | The comments that you want to record for the material class cutoff.

### See also

- Change Material Class Assignments
- Surface Locations
- Qualities Data Grid
- Material Classes Data Grid

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