Specify that decoders may reject non-zero probabilities for larger offset codes than...

diff --git a/doc/zstd_compression_format.md b/doc/zstd_compression_format.md
index 7955dae4abfb6fa08d10e5a5dcd6b86c6b4ce28c..8a60e56dfe5870de4a2f5ff15d3074def382bd18 100644 (file)
--- a/doc/zstd_compression_format.md
+++ b/doc/zstd_compression_format.md
@@ -1129,7 +1129,10 @@ If the last symbol makes cumulated total go above `1 << Accuracy_Log`,
 distribution is considered corrupted.
 If this process results in a non-zero probability for a value outside of the
 valid range of values that the FSE table is defined for, even if that value is
-not used, then the data is considered corrupted.
+not used, then the data is considered corrupted.  In the case of offset codes,
+a decoder implementation may reject a frame containing a non-zero probability
+for an offset code larger than the largest offset code supported by the decoder
+implementation.
 
 Then the decoder can tell how many bytes were used in this process,
 and how many symbols are present.