# Illegal Characters

When you enter certain names for objects or projects, some characters are automatically replaced with an underscore (“\_”). This is due to the parametric computation logic used internally. These characters can interfere with parametric equations and cause unexpected results.

For example, if you name an object **PierCap1+5**, OpenBrIM interprets this as a parameter named *PierCap1* plus the value *5*, rather than a single name. To avoid such conflicts, the following characters are not allowed:

**Illegal characters:**

* (space)
* `'` (single quote)
* `\` (backslash)
* `/` (forward slash)
* `|` (vertical bar / pipe)
* `?` (question mark)
* `*` (asterisk)
* `-` (hyphen)
* `+` (plus sign)
* `<` (less than)
* `>` (greater than)
* `:` (colon)
* `.` (period / dot)
* `@` (at sign)
* `&` (ampersand)
* `(` (left parenthesis)
* `)` (right parenthesis)
* `%` (percent sign)

All of these will be replaced automatically with an underscore (`_`) to ensure parametric stability.