$ pm_cat_plus_lines.pl
* asterisk_line_1
*
.dot_line
 plus_line_1 plus_line_2
* asterisk_line_3
 plus_line_3 plus_line_4
* asterisk_line_4
 plus_line_5 plus_line_6
plain_text_line_1
 plus_line_7
plain_text_line_2
 plus_line_8
*
*asterisk_line_6
*asterisk_line_7
plain_text_line_3