HP 33s hp 33s_user's manual_English_E_HDPM20PIE56.pdf - Page 190

„ To V  . „ To a line number: { V  label nnnn (nnnn < 10000). For example, { V  A0005. „ To a label: { V label -but only if program entry is not active (no program lines displayed; PRGM off). For example, { V A. Conditional Instructions Another way to alter the sequence of program execution is by a conditional test, a true/false test that compares two numbers and skips the next program instruction if the proposition is false. For instance, if a conditional instruction on line A0005 is º/ @ (that is, is x equal to zero?), then the program compares the contents of the X-register with zero. If the X-register does contain zero, then the program goes on to the next line. If the X-register does not contain zero, then the program skips the next line, thereby branching to line A0007. This rule is commonly known as "Do if true." Do next if true. M   M ... €N N Skip next if false. The above example points out a common technique used with conditional tests: the line immediately after the test (which is only executed in the "true" case) is a branch to another label. So the net effect of the test is to branch to a different routine under certain circumstances. There are three categories of conditional instructions: „ Comparison tests. These compare the X-and Y-registers, or the X-register and zero. 13-6 Programming Techniques