Custom attribute values

yes, you can try something like

<a href="#_ATT{Trainer_url}"> #_ATT{Trainer} </a>

Thanks, but then I had to create an additional attribute “Trainer_url” with all the options (“trainer-name-1”, “trainer-name-2” …). This will work, but in the backend you would have to select the trainer and the trainer link separately. Is it possible to use something like preg_replace() for #_ATT{Trainer} to replace “%20” by “-” and so on?

You should able to use str_replace to switch the spaces to a dash and strtolower to make it all lower case.

Okay, I′m using now 2 different attributes – I think that′s easier. But could you tell me in which file I could manipulate the attributes? Thanks!

The easiest and safest way to do that would be by creating a custom placeholder:

https://wp-events-plugin.com/tutorials/create-a-custom-placeholder-for-event-formatting/