Creating a blueprint for a front-end form

Does creating a blueprint for a front-end form (made with the Form plugin) differ from creating other blueprints? So far all my blueprints have been working fine, but now need to create two for forms I have on my website and they don't display correctly. Trying to find a reason. May it be due to the file naming?

I have a 'navigation_form.md' in a '_navigation' (modular) folder and 'navigation.yaml' file. And accordingly:
'contact_form.md' in a '_contact' (modular) folder and 'contact.yaml'.

Even before getting to displaying form data, a simple header neither works:

title: Newsletter
extends@: default

form:
  fields:
    tabs:
      type: tabs
      active: 1

      fields:
        gallery:
          type: tab
          title: Newsletter Fields

          fields:
            header.header:
              type: text
              label: Header
              validate:
                required: true

Indeed it was a matter of renaming the file to 'newsletter_form.yaml'. Should have checked before posting here. Sorry for taking your time, but maybe it will be useful for someone.