+=item B<-blao=i> or B<--blank-lines-after-opening-block=i>
+
+This control places a minimum of B<i> blank lines B<after> a line which B<ends>
+with an opening block brace of a specified type. By default, this only applies
+to the block of a named B<sub>, but this can be changed (see B<-blaol> below).
+The default is not to do this (B<i=0>).
+
+Please see the note below on using the B<-blao> and B<-blbc> options.
+
+=item B<-blbc=i> or B<--blank-lines-before-closing-block=i>
+
+This control places a minimum of B<i> blank lines B<before> a line which
+B<begins> with a closing block brace of a specified type. By default, this
+only applies to the block of a named B<sub>, but this can be changed (see
+B<-blbcl> below). The default is not to do this (B<i=0>).
+
+=item B<-blaol=s> or B<--blank-lines-after-opening-block-list=s>
+
+The parameter B<s> is a list of block type keywords to which the flag B<-blao>
+should apply. The section L<"Specifying Block Types"> explains how to list
+block types.
+
+=item B<-blbcl=s> or B<--blank-lines-before-closing-block-list=s>
+
+This parameter is a list of block type keywords to which the flag B<-blbc>
+should apply. The section L<"Specifying Block Types"> explains how to list
+block types.
+
+=item Note on using the B<-blao> and B<-blbc> options.
+
+These blank line controls introduce a certain minimum number of blank lines in
+the text, but the final number of blank lines may be greater, depending on
+values of the other blank line controls and the number of old blank lines. A
+consequence is that introducing blank lines with these and other controls
+cannot be exactly undone, so some experimentation with these controls is
+recommended before using them.
+
+For example, suppose that for some reason we decide to introduce one blank
+space at the beginning and ending of all blocks. We could do
+this using
+
+ perltidy -blao=2 -blbc=2 -blaol='*' -blbcl='*' filename
+
+Now suppose the script continues to be developed, but at some later date we
+decide we don't want these spaces after all. we might expect that running with
+the flags B<-blao=0> and B<-blbc=0> will undo them. However, by default
+perltidy retains single blank lines, so the blank lines remain.
+
+We can easily fix this by telling perltidy to ignore old blank lines by
+including the added parameter B<-kbl=0> and rerunning. Then the unwanted blank
+lines will be gone. However, this will cause all old blank lines to be
+ignored, perhaps even some that were added by hand to improve formatting. So
+please be cautious when using these parameters.
+