diff --git a/README.md b/README.md
index fa17f00d..04f86e35 100644
--- a/README.md
+++ b/README.md
@@ -66,10 +66,10 @@ Options
 
 ### Zoom levels and resolution
 
- * -z _zoom_: Max zoom level (default 14)
- * -Z _zoom_: Lowest (minzoom) zoom level (default 0)
- * -B _zoom_: Base zoom, the level at which point data is complete (default maxzoom)
- * -d _detail_: Detail at base zoom level (default 12, for tile resolution of 4096)
+ * -z _zoom_: Maxzoom: the highest zoom level for which tiles are generated (default 14)
+ * -Z _zoom_: Minzoom: the lowest zoom level for which tiles are generated (default 0)
+ * -B _zoom_: Base zoom, the level at and above which all points are included in the tiles (default maxzoom)
+ * -d _detail_: Detail at max zoom level (default 12, for tile resolution of 4096)
  * -D _detail_: Detail at lower zoom levels (default 12, for tile resolution of 4096)
  * -m _detail_: Minimum detail that it will try if tiles are too big at regular detail (default 7)
  * -b _pixels_: Buffer size where features are duplicated from adjacent tiles. Units are "screen pixels"--1/256th of the tile width or height. (default 5)
@@ -82,7 +82,7 @@ Options
 
 ### Point simplification
 
- * -r _rate_: Rate at which dots are dropped at lower zoom levels (default 2.5)
+ * -r _rate_: Rate at which dots are dropped at zoom levels below basezoom (default 2.5)
  * -g _gamma_: Rate at which especially dense dots are dropped (default 0, for no effect). A gamma of 2 reduces the number of dots less than a pixel apart to the square root of their original number.
 
 ### Doing more
diff --git a/man/tippecanoe.1 b/man/tippecanoe.1
index 3fbd4bb7..8754e4b3 100644
--- a/man/tippecanoe.1
+++ b/man/tippecanoe.1
@@ -71,11 +71,13 @@ specified, the files are all merged into the single named layer.
 .SS Zoom levels and resolution
 .RS
 .IP \(bu 2
-\-z \fIzoom\fP: Base (maxzoom) zoom level (default 14)
+\-z \fIzoom\fP: Maxzoom: the highest zoom level for which tiles are generated (default 14)
 .IP \(bu 2
-\-Z \fIzoom\fP: Lowest (minzoom) zoom level (default 0)
+\-Z \fIzoom\fP: Minzoom: the lowest zoom level for which tiles are generated (default 0)
 .IP \(bu 2
-\-d \fIdetail\fP: Detail at base zoom level (default 12, for tile resolution of 4096)
+\-B \fIzoom\fP: Base zoom, the level at and above which all points are included in the tiles (default maxzoom)
+.IP \(bu 2
+\-d \fIdetail\fP: Detail at max zoom level (default 12, for tile resolution of 4096)
 .IP \(bu 2
 \-D \fIdetail\fP: Detail at lower zoom levels (default 12, for tile resolution of 4096)
 .IP \(bu 2
@@ -95,7 +97,7 @@ specified, the files are all merged into the single named layer.
 .SS Point simplification
 .RS
 .IP \(bu 2
-\-r \fIrate\fP: Rate at which dots are dropped at lower zoom levels (default 2.5)
+\-r \fIrate\fP: Rate at which dots are dropped at zoom levels below basezoom (default 2.5)
 .IP \(bu 2
 \-g \fIgamma\fP: Rate at which especially dense dots are dropped (default 0, for no effect). A gamma of 2 reduces the number of dots less than a pixel apart to the square root of their original number.
 .RE
@@ -168,7 +170,7 @@ coordinated with the base zoom level and dot\-dropping rate. You can use this sh
 calculate the appropriate marker\-width at high zoom levels to match the fraction of dots
 that were dropped at low zoom levels.
 .PP
-If you used \fB\fC\-z\fR to change the base zoom level or \fB\fC\-r\fR to change the
+If you used \fB\fC\-B\fR or \fB\fC\-z\fR to change the base zoom level or \fB\fC\-r\fR to change the
 dot\-dropping rate, replace them in the \fB\fCbasezoom\fR and \fB\fCrate\fR below.
 .PP
 .RS
@@ -193,7 +195,9 @@ awk 'BEGIN {
 At every zoom level, line and polygon features are subjected to Douglas\-Peucker
 simplification to the resolution of the tile.
 .PP
-For point features, it drops 1/2.5 of the dots for each zoom level above the base.
+For point features, it drops 1/2.5 of the dots for each zoom level above the
+point base zoom (which is normally the same as the \fB\fC\-z\fR max zoom, but can be
+a different zoom specified with \fB\fC\-B\fR if you have precise but sparse data).
 I don't know why 2.5 is the appropriate number, but the densities of many different
 data sets fall off at about this same rate. You can use \-r to specify a different rate.
 .PP