Do the Custom Variable Index number need to remain consistent globally to a Piwik installation?

Read the following in Docs about customer variable indexes. Does this mean that I can only ever store the same 5 types of value globally to a single Piwik installation?
Currently I am using those index numbers differently for different page loads, so on /page1.aspx index 5 might be “Type” while on /page2.aspx index 5 might be “Author”.
Can I do this, or will it just overwrite?? If it will overwrite, is that a limit across a whole Piwik installation, or specific to one SiteId only…??

“Important: a given custom variable name must always be stored in the same “index”. For example, if you choose to store the variable name = “Gender” in index = 1 and you record another custom variable in index = 1, then the “Gender” variable will be deleted and replaced with the new custom variable stored in index 1.”

Many thanks in advance!

Gareth

No, it doesn’t have to stay consistent. However it’s better to stay consistent if you plan to use Custom Segments involving custom variables.