-Return the history entry at position \fIoffset\fP, starting from
-\fBhistory_base\fP.
-If there is no entry there, or if \fIoffset\fP
-is greater than the history length, return a \fBNULL\fP pointer.
+Return the history entry at position \fIoffset\fP.
+The range of valid values of \fIoffset\fP starts at \fBhistory_base\fP
+and ends at \fBhistory_length\fP \- 1.
+If there is no entry there, or if \fIoffset\fP is outside the valid
+range, return a \fBNULL\fP pointer.