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     An inference rule specifies the commands to be executed if a
     target and dependent with certain extensions are out-of-date.
     The rule applies to a single target and dependent that have the
     same base name. You cannot use an inference rule to match a
     dependency that specifies more than one target or dependent.
 
     Use an inference rule to apply one commands block to more than one
     dependency. Because rules can be specified in TOOLS.INI and
     targets can be specified on the command line, inference rules can
     make a makefile unnecessary.
 
     You can define your own rules or use predefined inference rules.
     Rules can be defined in the makefile or in TOOLS.INI. If a rule
     is defined more than once, NMAKE applies a precedence decision.
     See: ◄Defining an Inference Rule►
          ◄Precedence Among Inference Rules►
          ◄Predefined Inference Rules►
          ◄The TOOLS.INI File►
 
     The .SUFFIXES list determines priorities for applying rules.
     Inference rules apply only to extensions listed in .SUFFIXES.
     See: ◄.SUFFIXES Directive►
 
     How NMAKE Uses Inference Rules
 
     Inference rules are used in the following situations:
 
        ■ If NMAKE evaluates a dependency that has no commands, it
          checks .SUFFIXES and the current or specified directory, then
          searches for a rule that matches the extensions of the target
          and an existing dependent file. The dependent's extension
          must be listed in .SUFFIXES. If more than one matching file
          exists, .SUFFIXES determines which rule is used.
 
        ■ If a dependent file doesn't already exist in the current or
          specified directory, and there is not another dependency that
          specifies that dependent as a target, NMAKE looks for an
          inference rule that shows how to create the missing dependent
          from another file with the same base name.
 
        ■ If a dependency specifies a target but no dependent and no
          commands, NMAKE can use a rule to create the target.
 
        ■ If a target is specified on the command line and there is no
          makefile, or the makefile has no dependency that specifies
          the target, NMAKE can use a rule to create the target.
 
     Cautions
 
     If a target is used in more than one single-colon dependency, an
     inference rule might not be applied as expected.
     See: ◄Accumulating Targets in Dependencies►
 
     NMAKE might invoke a rule for an inferred dependent even if an
     explicit dependent is specified.
     See: ◄Inferred Dependents►
 
     Example
 
          .c.obj:
            cl /c $<
 
          sample.obj :
 
     This makefile contains an inference rule and a dependency. The
     rule tells NMAKE how to build an .OBJ file from a .C file. The
     predefined macro $< represents a dependent that has a later time
     stamp than the target. The dependency specifies a target but no
     dependent or command. However, given the target's base name and
     extension, plus the inference rule, NMAKE has enough information
     to build the target.
 
     After verifying that .c is in the .SUFFIXES list, NMAKE looks for
     a file with the same base name as the target and with the .C
     extension. If SAMPLE.C exists (and no files with higher-priority
     extensions exist), NMAKE compares the time stamps. If SAMPLE.C has
     changed more recently than SAMPLE.OBJ., NMAKE compiles it using
     the CL command listed in the inference rule:
 
          cl /c sample.c
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