Function: put-text-property

Set one property of the text from START to END.
The third and fourth arguments PROPERTY and VALUE
specify the property to add.
If the optional fifth argument OBJECT is a buffer (or nil, which means
the current buffer), START and END are buffer positions (integers or
markers). If OBJECT is a string, START and END are 0-based indices into it.

(fn START END PROPERTY VALUE &optional OBJECT)