{  (Verb)

CATALOGUE (1)  {y forms a catalogue from the atoms of its  arguments, its shape being the chain of the shapes of the opened items of y, and the common shape of the boxed results is $y. The case {a;<b is called the Cartesian product of a and b. Thus:

	  c=. {'ht';'ao';'gtw'	 	   
	  n=. { 10 11 ; i.2 3 
	  c				           n 
+---+---+---+   +----+----+----+
|hag|hat|haw|   |10 0|10 1|10 2|
+---+---+---+   +----+----+----+
|hog|hot|how|   |10 3|10 4|10 5|
+---+---+---+   +----+----+----+	
+---+---+---+   +----+----+----+
|tag|tat|taw|   |11 0|11 1|11 2|
+---+---+---+   +----+----+----+
|tog|tot|tow|   |11 3|11 4|11 5|
+---+---+---+   +----+----+----+
   $c              $n
2 2 3           2 2 3

FROM (0 _)  If x is an integer in the range from –#y to <:#y, then x{y selects item (#y)|x from y. More generally, x may be a boxed list, whose successive elements are (possibly) boxed lists that specify selection along successive axes of y. For example:

	  y			            2 0{y
abcdef			       mnopqr
ghijkl			       abcdef
mnopqr
	  (<2 0){y        (<2 0;1 3){y
m				           np
				            bd

Finally, if any r=.>j{>x used in the selection  is itself boxed,  selection is made by the indices along that axis (i.j{$y) that do not occur in >r. For example:

   (<(<<2 0),(<<1 3)){y
gikl