There are areas of specialization that are unique to each country or areas of philately. United States collectors are avid about plate blocks and stamp collectors in the rest of the world think we are crazy. Israel collectors esteem tabs. British Commonwealth collectors collect gutter pairs and marginal markings. German area collectors collect Zusammendrucke. Stamps that go into stamp booklets are printed in panes (usually of six) and those panes are printed in sheets of various sizes. The United States post office does not issue these large uncut sheets to collectors so that all US philatelists can collect is booklet panes and booklets. German philatelists have additional options as the German post office sells full booklet sheets to philatelists. These are uncut sheets, often with 100-220 subjects on the sheet. German collectors collect them in full sheets, as panes and in combinations that never would be issued to the public but which are possible from breaking up the sheets. Zusammendrucke are part of every decent specialized German collection. They are listed in the Michel specialized catalog of German stamps and, just as with US plate blocks and Israeli tabs, there are some remarkable premiums for ordinary stamps in unusual combinations.