@@ -480,30 +480,36 @@ the first pattern, followed by one or more `!` exception patterns.

 ## FROM

-    FROM <image>

+    FROM <image> [AS <name>]

 Or

-    FROM <image>:<tag>

+    FROM <image>[:<tag>] [AS <name>]

 Or

-    FROM <image>@<digest>

+    FROM <image>[@<digest>] [AS <name>]

-The `FROM` instruction sets the [*Base Image*](glossary.md#base-image)

-for subsequent instructions. As such, a valid `Dockerfile` must have `FROM` as

-its first instruction. The image can be any valid image – it is especially easy

-to start by **pulling an image** from the [*Public Repositories*](https://docs.docker.com/engine/tutorials/dockerrepos/).

+The `FROM` instruction initializes a new build stage and sets the 

+[*Base Image*](glossary.md#base-image) for subsequent instructions. As such, a 

+valid `Dockerfile` must have `FROM` as its first instruction. The image can be

+any valid image – it is especially easy to start by **pulling an image** from 

+the [*Public Repositories*](https://docs.docker.com/engine/tutorials/dockerrepos/).

 - `FROM` must be the first non-comment instruction in the `Dockerfile`.

-- `FROM` can appear multiple times within a single `Dockerfile` in order to create

-multiple images. Simply make a note of the last image ID output by the commit

-before each new `FROM` command.

+- `FROM` can appear multiple times within a single `Dockerfile` in order to 

+create multiple images or use one build stage as a dependency for another. 

+Simply make a note of the last image ID output by the commit before each new 

+`FROM` command. Each `FROM` command resets all the previous commands.

-- The `tag` or `digest` values are optional. If you omit either of them, the builder

-assumes a `latest` by default. The builder returns an error if it cannot match

-the `tag` value.

+- Optionally a name can be given to a new build stage. That name can be then

+used in subsequent `FROM` and `COPY --from=<name|index>` commands to refer back

+to the image built in this stage.

+

+- The `tag` or `digest` values are optional. If you omit either of them, the 

+builder assumes a `latest` tag by default. The builder returns an error if it

+cannot match the `tag` value.

 ## RUN

@@ -937,6 +943,13 @@ All new files and directories are created with a UID and GID of 0.

 > If you build using STDIN (`docker build - < somefile`), there is no

 > build context, so `COPY` can't be used.

+Optionally `COPY` accepts a flag `--from=<name|index>` that can be used to set

+the source location to a previous build stage (created with `FROM .. AS <name>`)

+that will be used instead of a build context sent by the user. The flag also 

+accepts a numeric index assigned for all previous build stages started with 

+`FROM` command. In case a build stage with a specified name can't be found an 

+image with the same name is attempted to be used instead.

+

 `COPY` obeys the following rules:

 - The `<src>` path must be inside the *context* of the build;