# Reserved Words and confusing errors

**URL:** https://forum.makecode.com/t/reserved-words-and-confusing-errors/872
**Category:** Arcade
**Created:** [December 7, 2019, 11:49pm UTC](https://forum.makecode.com/t/reserved-words-and-confusing-errors/872 "2019-12-07T23:49:22Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![kjw](https://avatars.discourse-cdn.com/v4/letter/k/e79b87/32.png) [@kjw](https://forum.makecode.com/u/kjw)
#### Post date: [December 7, 2019, 11:49pm UTC](https://forum.makecode.com/t/reserved-words-and-confusing-errors/872/1 "2019-12-07T23:49:22Z")

</div>

What’s the handling of reserved words / clashing variables from Blocks supposed to be like? I noticed sometime ago that `screen` cannot be used as a variable name. It produced and still produces an error that would confuse a novice programmer.

> `Cannot redeclare block-scoped variable `screen`.`

I just played around with a few other likely candidates and MakeCode seems to deal with `let` and `image` ok with some “under the covers renaming” either underscore prefix or a numeric suffix.

![makecode-arcade-reserved-words-ii-0.14.48](https://us1.discourse-cdn.com/flex020/uploads/makecode/original/1X/1e6688feac68145e1933bd48983f8f18f32f2eca.png)

Was `screen` missed from some manually created list? Or has the creation of an automatically managed list failed? If you are unlucky on ordering then you can clash with the variable naming/renaming going on under the covers.