Add element to org-refile-targets

Question

I am keeping a common init.el for work and private on separate machines. So dependent on my machine I have common settings and machine dependent settings.

How do I get to add an element to the org-refile-targets variable?

This works well:

(setq org-refile-targets '(("~/sync/common.org"  :maxlevel . 2)
                           ("~/org/machine1.org" :maxlevel . 2)))

How can I separate this variable definition?

Not working:

 (add-to-list 'org-refile-targets ("~/sync/common.org"  :maxlevel . 2))
[...]
 (add-to-list 'org-refile-targets ("~/org/machine1.org" :maxlevel . 2))

Testing results in an error of:

*** Eval error *** Invalid function: "~/org/machine1.org"

Answer 1

If you try to add a list such way it will be evaluated and interpreted as function. Quote it.

(add-to-list 'org-refile-targets '("~/sync/common.org"  :maxlevel . 2))