DAX function

CROSSFILTER — DAX function reference

Set cross-filter direction.

Syntax

dax

CALCULATE(<expression>, CROSSFILTER(<columnName1>, <columnName2>, <direction>))

dax

CALCULATE([Sales], CROSSFILTER(Sales[CustID], Customer[CustID], BOTH))

→ A number

dax

CALCULATE(DISTINCTCOUNT(Customer[CustomerID]), CROSSFILTER(Sales[CustID], Customer[CustID], BOTH))

→ Distinct customers filtered by a Product-side selection, via bidirectional filtering just for this measure

dax

CALCULATE(SUM(Sales[Amount]), CROSSFILTER(Sales[CustID], Customer[CustID], NONE))

→ Disables the relationship entirely for this calculation

Direction NONE temporarily removes filtering across that relationship altogether (not just direction) — the way to compute "as if the tables were unrelated" without physically deleting the relationship.
Turning a normally single-direction relationship BOTH inside CROSSFILTER can introduce ambiguous filter paths in models with multiple relationships between the same tables, causing a circular-dependency-style error at evaluation time.

From Relationships