diff --git a/Point_set_processing_3/doc/Point_set_processing_3/Point_set_processing_3.txt b/Point_set_processing_3/doc/Point_set_processing_3/Point_set_processing_3.txt
index 563df93bada..d133e3e67e3 100644
--- a/Point_set_processing_3/doc/Point_set_processing_3/Point_set_processing_3.txt
+++ b/Point_set_processing_3/doc/Point_set_processing_3/Point_set_processing_3.txt
@@ -153,6 +153,9 @@ but also regularizes downsampled points. This is an implementation of
 the WLOP (Weighted Locally Optimal Projection) algorithm 
 <a href="http://web.siat.ac.cn/~huihuang/WLOP/WLOP_page.html">[Huang et al. 2009]</a>.
 This algorithm is much slower.
+Concurrency_tag controls what mode will the algorithm will run in. There two tags available: Parallel_tag, Sequential_tag.
+When Parallel_tag is used, algorithm will run in parallel mode based On Thread Building Blocking, which will achieve great performance improvement;
+When Sequential_tag is used, algorithm will run in normal sequential mode.
  
 \subsection Point_set_processing_3Example_3 Grid simplification example