# byond_build var (savefile)

Source: https://ref.dm-lang.org/savefile/var/byond_build
Added in BYOND 515.

### Default value
> 0

Sometimes when transitioning between BYOND versions you'll want to keep a savefile in a condition where it can be read by older versions. The `byond_version` var tells it to avoid using newer savefile features (unless forced to) above a certain build number. (The build number changes more often than the BYOND version number.) A value of 0 means not to worry about it.

This can be changed on a per-savefile basis so that you can use newer features in some files and avoid changing others. For instance, character saves might want to go on using older features for a while, but for saving parts of the map you might prefer to allow newer features to be used.

The default savefile compatibility version can be set at compile-time:

```dm
savefile/byond_build = 1600  // do not use savefile features from BYOND build 1601 onward
```

### See also
- [savefile](https://ref.dm-lang.org/savefile/index.md)
- [byond_version var (savefile)](https://ref.dm-lang.org/savefile/var/byond_version.md)
- [byond_version var (world)](https://ref.dm-lang.org/world/var/byond_version.md)
- [byond_build var (world)](https://ref.dm-lang.org/world/var/byond_build.md)