+It must be a string \(program name\) or list of strings \(name and its args\)."
+ :type '(repeat string)
+ :group 'sha1)
+
+(defcustom sha1-use-external (condition-case ()
+ (executable-find (car sha1-program))
+ (error))
+ "*Use external SHA1 program.
+If this variable is set to nil, use internal function only."
+ :type 'boolean
+ :group 'sha1)