# Multipart UR Examples
`envelope` emits UR strings. Multipart QR output is handled by the companion
`mur` tool, which splits a UR into fountain-coded QR frames or an animated QR
sequence.
## Create a UR with `envelope`
Any envelope UR can be passed to `mur`. This example creates a small salted
envelope:
```sh
For a larger backup, use the command that creates the document you want to put
on paper, then pass that UR to `mur`.
## Numbered QR Frames
Use `mur frames` to write one PNG per multipart frame:
```sh
mur frames --max-fragment-len 80 --output backup-frames "$ENVELOPE"
```
`--max-fragment-len` controls the maximum fragment length used for fountain
coding. Smaller fragments create more QR frames, but each frame is easier for a
scanner to read. Larger fragments create fewer frames, but each QR code is
denser.
Useful frame options include:
```sh
mur frames \
--max-fragment-len 80 \
--size 768 \
--correction high \
--cycles 4 \
--output backup-frames \
"$ENVELOPE"
```
The output directory will contain numbered PNG files suitable for printing one
frame per page.
## Animated QR
Use `mur animate` to produce an animated QR sequence:
```sh
mur animate --max-fragment-len 80 --cycles 4 --output backup.gif "$ENVELOPE"
```
The default animation format is GIF. `--fps` controls playback speed, and
`--cycles` controls how many complete passes through the frame set are emitted.
## Read from Standard Input
Both `mur frames` and `mur animate` accept `-` to read the UR from standard
input:
```sh
envelope subject type string "paper backup example" |
envelope salt |
mur frames --max-fragment-len 80 --output backup-frames -
```
This keeps the generated UR out of the shell history.