The "single-rate three-color marker" described by RFC 2697 allows for temporary bursts. The bursts are allowed when the line was under-used before they appeared. A more predictable algorithm is described in RFC 2698, which proposes a "double-rate three-color marker". RFC 2698 defines a new parameter, the Peak Information Rate (PIR). RFC 2859 describes the "Time Sliding Window Three Colour Marker" which meters a traffic stream and marks packets based on measured throughput relative to two specified rates: Committed Target Rate (CTR) and Peak Target Rate (PTR).