RCL type-1 matrix field was a type of re-filtration processor used by the Cardassians.
In 2369, the re-filtration processors began breaking down aboard the station Deep Space 9. Jadzia Dax studying a schematic of the processors on a PADD thought the processor looked like something the Cardassians might have taken from the Romulans and was having trouble with identifying the type. She thought it could have been a RCL type-1 matrix field or a RCL type-2 matrix field. (DS9: "Dax")