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.. 62