SAS - pdf output with changed bookmarks

My problem is as follows - I have two datasets, out of which I create through macro loop 2 * 2 graphs. I plot these two graphs into the pdf file having the first 2 graphs on the page 1 and the other graphs on the page 2.

The output pdf is fine, the only thing I would like to change are bookmarks. I would like them to contain some detailed information about the graphs - one separate original bookmark per each graph.

Is there some simple way how to do that ? I have found out some complicated solutions through proc report, but is there any easy way for my current code ?

data out_i_a; set sashelp.retail; run;
data out_ii_b; set sashelp.retail; run; 

data y;
length saz tef $100;
input saz $ tef $; 
datalines;
i a 
ii b
;
run;

%macro grafy();
proc sql;
 select count(*) into: pocet from y;
quit;

ods _all_ close;
goptions hsize=20cm vsize=8cm;
ods pdf file="\\srv05\nt05a\GRAF\TOT_testing.pdf";
ods layout gridded columns=1;


%do i=1 %to &pocet;
data _null_;
  set y (obs=&i);
 call symput("saz" ,strip(saz));
 call symput("tef" ,strip(tef));
run;

ods region;
ods pdf text="&saz._&tef";
symbol1 interpol=join height=10pt VALUE=NONE LINE=1 WIDTH=1 CV= _STYLE_;
symbol2 interpol=join height=10pt VALUE=NONE LINE=1 WIDTH=1 CV= _STYLE_;
Legend1 value=('SALES' 'YEAR');
axis1 label=('# sales');
axis3 label=('# year');
axis2 label=('date');
proc gplot data= out_&saz._&tef;
plot (SALES)*DATE   / overlay skipmiss
VAXIS=AXIS1 
HAXIS=AXIS2 LEGEND=Legend1;
plot2 (YEAR)*DATE / overlay skipmiss
VAXIS=AXIS3
HAXIS=AXIS2 LEGEND=Legend1;
run;

ods region;
symbol1 interpol=join height=10pt VALUE=NONE LINE=1 WIDTH=1 CV= _STYLE_;
symbol2 interpol=join height=10pt VALUE=NONE LINE=1 WIDTH=2 CV= _STYLE_;
Legend1 value=('year' 'month');
axis1 label=('in %, p.a.');
axis2 label=('date');
proc gplot data= out_&saz._&tef;
 plot (YEAR MONTH)*DATE   / overlay skipmiss
 VAXIS=AXIS1 
 HAXIS=AXIS2 LEGEND=Legend1;
run;
%end;

ods layout end;
ods pdf close;

%mend;
%grafy();

The current bookmarks - to be changed - are created automatically and are as follows:

The GPlot Procedure - Plot of YEAR by DATE

The GPlot Procedure - Plot of MONTH by DATE

The GPlot Procedure - Plot of YEAR by DATE

The GPlot Procedure - Plot of MONTH by DATE

Before each Proc GPLOT you can issue an ODS PROCLABEL statement to replace the default text shown in the bookmarks top level.
Add / description= to each PLOT statement to specify the bookmark second level text.

For example:

ODS PROCLABEL "&saz &tef SALES";  /* ADD THIS */

proc gplot data= out_&saz._&tef;
plot (SALES)*DATE   / overlay skipmiss

DESCRIPTION = "by Date" /* ADD THIS */

VAXIS=AXIS1 
HAXIS=AXIS2 LEGEND=Legend1;
plot2 (YEAR)*DATE / overlay skipmiss
VAXIS=AXIS3
HAXIS=AXIS2 LEGEND=Legend1;