diff --git a/graphics-protocol.asciidoc b/graphics-protocol.asciidoc
index a3a182cbc..c6083fe55 100644
--- a/graphics-protocol.asciidoc
+++ b/graphics-protocol.asciidoc
@@ -199,15 +199,51 @@ printable characters and spaces. The string will be `OK` if reading the pixel
 data succeeded or an error message. 
 
 
+== Display images on screen
+
+Every transmitted image can be displayed an arbitrary number of times on the
+screen, in different locations, using different parts of the source image, as
+needed. You can either simultaneously transmit and display an image using the
+action `a=T`, or first transmit the image with a id, such as `i=10` and then display
+it with `a=p,i=10` which will display the previously transmitted image at the current
+cursor position.
+
+=== Controlling displayed image layout
+
+The image is rendered at the current cursor position, from the upper left corner of
+the current cell. You can also specify extra `X=3` and `Y=4` pixel offsets to display from 
+a different origin within the cell. Note that the offsets must be smaller that the size of the cell.
+
+By default, the entire image will be displayed (images wider than the available
+width will be truncated on the right edge). You can choose a source rectangle (in pixels)
+as the part of the image to display. This is done with the keys: `x, y, w, h` which specify
+the top-left corner, width and height of the source rectangle.
+
+You can also ask the terminal emulator to display the image in a specified rectangle
+(num of columns / num of lines), using the control codes `c,r`. `c` is the number of columns
+and `r` the number of rows. The image will be scaled (enlarged/shrunk) as needed to fit 
+the specified area. Note that if you specify a start cell offset via the `X,Y` keys, it is not
+added to the number of rows/columns.
+
+Finally, you can specify the image *z-index*, i.e. the vertical stacking order. Images
+placed in the same location with different z-index values will be blended if
+they are semi-transparent. You can specify z-index values using the `z` key.
+Negative z-index values mean that the images will be drawn under the text. This
+allows rendering of text on top of images.
+
 == Control data reference
 
 The table below shows all the control data keys as well as what values they can
 take, and the default value they take when missing.
 
+[cols="^1,<3,^1,<6"]
 |===
 |Key | Value | Default | Description
 
-| `a` | Single character. `(t, T, q, p)` | `t` | The overall action this graphics command is performing.
+| `a` | Single character. `(t, T, p)` | `t` | The overall action this graphics command is performing.
+
+4+^h| Keys for image transmission
+
 | `f` | Positive integer. `(24, 32, 100)`. | `32` | The format in which the image data is sent.
 | `t` | Single character. `(d, f, t, s)`. | `d` | The transmission medium used.
 | `s` | Positive integer. | `0` | The width of the image being sent.
@@ -215,7 +251,18 @@ take, and the default value they take when missing.
 | `S` | Positive integer. | `0` | The size of data to read from a file.
 | `O` | Positive integer. | `0` | The offset from which to read data from a file.
 | `i` | Positive integer. `(0 - 4294967295)` | `0` | The image id
-| `o` | Single character. `only z` | - | The type of data compression.
+| `o` | Single character. `only z` | null | The type of data compression.
 | `m` | zero or one | `0` | Whether there is more chunked data available.
 
+4+^h| Keys for image display
+
+| `x` | Positive integer | `0` | The left edge (in pixels) of the image area to display
+| `y` | Positive integer | `0` | The top edge (in pixels) of the image area to display
+| `w` | Positive integer | `0` | The width (in pixels) of the image area to display. By default, the entire width is used.
+| `h` | Positive integer | `0` | The height (in pixels) of the image area to display. By default, the entire height is used
+| `X` | Positive integer | `0` | The x-offset within the first cell at which to start displaying the image
+| `Y` | Positive integer | `0` | The y-offset within the first cell at which to start displaying the image
+| `c` | Positive integer | `0` | The number of columns to display the image over
+| `r` | Positive integer | `0` | The number of rows to display the image over
+| `z` | Integer          | `0` | The *z-index* vertical stacking order of the image
 |===