1 .	\"DS - display.  If .DS C, center; L, left-adjust; I, indent.
2 .de DS
3 .KS
4 .nf
5 .\\$1D \\$2 \\$1
6 .ft 1
7 .if !\\n(IF \{\
8 .	ps \\n(PS
9 .	ta 5n 10n 15n 20n 25n 30n 35n 40n 45n 50n 55n 60n 65n 70n 75n 80n
10 .	ie \\n(VS>=41 .vs \\n(VSu
11 .	el .vs \\n(VSp\}
12 ..
13 .de D
14 .ID \\$1
15 ..
16 .de CD
17 .XD
18 .ce 1000
19 ..
20 .de ID
21 .XD
22 .if t .in +0.5i
23 .if n .in +8
24 .if \\n(.$ .if !"\\$1"I" .if !"\\$1"" .in \\n(OIu
25 .if \\n(.$ .if !"\\$1"I" .if !"\\$1"" .in +\\$1n
26 ..
27 .de LD
28 .XD
29 ..
30 .de XD
31 .nf
32 .nr OI \\n(.i
33 .sp \\n(DVu
34 ..
35 .de BD \" block display: save everything, then center it.
36 .XD
37 .nr BD 1
38 .nf
39 .in \\n(OIu
40 .di DD
41 ..
42 .	\"DE - display end
43 .de DE
44 .ce 0
45 .if \\n(BD>0 .DF
46 .nr BD 0
47 .in \\n(OIu
48 .KE
49 .sp \\n(DVu
50 .fi
51 ..
52 .de DF \" finish a block display to be recentered.
53 .di
54 .if \\n(dl>\\n(BD .nr BD \\n(dl
55 .if \\n(BD<\\n(.l .in (\\n(.lu-\\n(BDu)/2u
56 .nr EI \\n(.l-\\n(.i
57 .ta \\n(EIuR
58 .nf
59 .DD
60 .in \\n(OIu
61 ..