0.1. Syntax: Balanced plus signs (from 1 to 5)

1. Title Level 1

1.1. Title Level 2

1.1.1. Title Level 3

1.1.1.1. Title Level 4

1.1.1.1.1. Title Level 5

1.2. Label: Between brackets, alphanumeric [A-Za-z0-9_-]

2. Title Level 1

2.1. Title Level 2

2.1.1. Title Level 3

2.1.1.1. Title Level 4

2.1.1.1.1. Title Level 5

2.2. Syntax: Spaces around and/or inside are allowed (and ignored)

2.2.1. Title Level 3

2.2.2. Title Level 3

2.2.3. Title Level 3

2.2.4. Title Level 3

2.2.5. Title Level 3

2.2.6. Title Level 3

2.3. Invalid: Unbalanced plus signs

+Not Title

++Not Title+

+++Not Title++++

2.4. Invalid: Level deeper than 5

++++++Not Title 6++++++

+++++++Not Title 7+++++++

2.5. Invalid: Space between title and label

+Not Title+ [label1]

2.6. Invalid: Space inside label

+Not Title+[ label ]

2.7. Invalid: Strange chars inside label

+Not Title+[la/bel]