TYPO3 Core

There is no common mark-up in the CMS backend for checkbox+labels in forms.
With the inclusion of Bootstrap we decide for the Bootstrap HTML5 markup syntax in forms:

See http://getbootstrap.com/css/#forms for preview and mark-up.

Forms do not receive a special markup.
Normal forms without layout (not horizontal, not filter-bar, not inline) include this syntax:

<form role="form">

  <div class="form-group">
    <label for="text">Label text</label>
    <input type="file" id="text">
    <p class="help-block">Example block-level help text here.</p>
  </div>

  <div class="checkbox">
    <label>
      <input type="checkbox">
      Check me out
    </label>
  </div>

</form>

In this first step we migrate the checkbox html towards HTML5 mark-up:

1. Wrap checkbox group within

   <div class="checkbox"></div>

2. Move Input field into the

   <label>…</label>

3. Move the label text into the

   <label>…</label>

   after the input checkbox

Why?
Ofter the checkbox and radio inputs are grouped and bring one description label for the group:

Behave like: [x] A
[-] B

Therefore the <label> tag is not formatted bold and the

<div class="checkbox">

can also bring another group label.