Data-preparation-workflow.md

@@ -181,6 +181,7 @@ Check the segmentation occasionally. If a lot of neighboring pages are getting s
 path/to/volume-cartographer/build/bin/vc_merge_pointsets -i path/to/dir_containing_all_pointsets -o path/to/output_dir
 ``` 
 Note: vc_merge_pointsets takes a directory that contains all vcps files you wish to merge as input. Put all vcps files in there. You will need to rename them, but make sure to keep the .vcps extension.
+Note: Use the --prune flag to prune the pointsets during the merge. **Important: every vcps file must be named the last slice number of that segmentation that you wish to keep (example: a segmentation that goes to 1200 slices but is only valid until 1150 should be named 1150.vcps)** (Coming soon)
 
 * Convert the vcps file into a point cloud. Do this by using vc_convert_pointset. Usage:
 ```