> For the complete documentation index, see [llms.txt](https://docs.intentable.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.intentable.io/intent-structure/variables.md).

# Variables

Variables can be used either in calls params and in called function input params.

There is no type check for variables, so it is the responsible of the FCT builder & activator to do type checking offline.

In order to allow variables as part of a standard EIP712 message, rarely used values were chosen to represent variables.

Variables can be created from multiple sources:

* Injected by the activator when executing an FCT (External) 
* Returned data for previous calls (Returned Data)
* Runtime information taken from the EVM (Generic)