.pg !!
.lm CMDTAB.nf
 ________
|        |
|        |
|   .OB  |
|        |
|________|
.fi.lm LEFTMG
.hl 1;OB command
.ix OVERBAR
.ix OB
The overbar command (OB) will overprint the previous line with the
specified characters one line above the current line.
.s.lm +7.nf
 _________ ___________________________________
|         |                                   |
|   .OB   |    [n] [;text] or                 |
|         |    text on following line         |
|_________|___________________________________|
.fi.lm LEFTMG.s
The OB command will overprint the previous line with the text one line above
the current line.
.b
The parameter n, is optional and specifies how far above the current line
the text should be placed.
Like the center command, the text for OB can appear on the same line as the
command, when preceded by a semi-colon, or it can be placed on the line
immediately following the OP command.
.s 2;.lm LEFTMG
Defaults:
.s;.lm +7
Default paper movement is 1 full line. n can be 1/8 to 1 (8/8) line movement.
If n is less than 0 or greater than 1, n is set to 1.
.b.i-7
Notes:
.b
This command is typically used in equations to generate over-scores in
displayed equations
while allowing the overscores to be placed directly above the overscored text.
See EQ example for use of this.