And now, the update. These changes arrange things so that binary files include "transition" entries for minimum time values; these entries eliminate localtime guesswork in handling low-valued time stamps.

The bad news: binary files grow slightly as a result of these changes.
The good news: there are no changes in the output of "zdump -v" applied to

before-and-after versions of all the binary files generated by a "make install."

Changes are attached and appear in mangled form below; these are relative to the github version of zic.c after the rollback in the earlier message today.

    @dashdashado

1.2
2805 lines
1.4
2813 lines
*** /tmp/,azic.c    2014-05-01 01:51:36.998933800 -0400
--- /tmp/,bzic.c    2014-05-01 01:51:37.092534000 -0400
***************
*** 1480,1493 ****
        fromi = 0;
        while (fromi < timecnt && attypes[fromi].at < min_time)
            ++fromi;
-         if (isdsts[0] == 0)
-             while (fromi < timecnt && attypes[fromi].type == 0)
-                 ++fromi;    /* handled by default rule */
        for ( ; fromi < timecnt; ++fromi) {
!             if (toi != 0 && ((attypes[fromi].at +
                gmtoffs[attypes[toi - 1].type]) <=
!                 (attypes[toi - 1].at + gmtoffs[toi == 1 ? 0
!                 : attypes[toi - 2].type]))) {
                    attypes[toi - 1].type =
                        attypes[fromi].type;
                    continue;
--- 1480,1490 ----
        fromi = 0;
        while (fromi < timecnt && attypes[fromi].at < min_time)
            ++fromi;
        for ( ; fromi < timecnt; ++fromi) {
!             if (toi > 1 && ((attypes[fromi].at +
                gmtoffs[attypes[toi - 1].type]) <=
!                 (attypes[toi - 1].at +
!                 gmtoffs[attypes[toi - 2].type]))) {
                    attypes[toi - 1].type =
                        attypes[fromi].type;
                    continue;
***************
*** 1532,1537 ****
--- 1529,1541 ----
        --timecnt32;
        ++timei32;
    }
+     /*
+     ** Output an INT32_MIN "transition" if appropriate--see below.
+     */
+     if (timei32 > 0 && ats[timei32] > INT32_MIN) {
+         --timei32;
+         ++timecnt32;
+     }
    while (leapcnt32 > 0 && !is32(trans[leapcnt32 - 1]))
        --leapcnt32;
    while (leapcnt32 > 0 && !is32(trans[leapi32])) {
***************
*** 1698,1704 ****
#undef DO
        for (i = thistimei; i < thistimelim; ++i)
            if (pass == 1)
!                 puttzcode(ats[i], fp);
            else    puttzcode64(ats[i], fp);
        for (i = thistimei; i < thistimelim; ++i) {
            unsigned char    uc;
--- 1702,1713 ----
#undef DO
        for (i = thistimei; i < thistimelim; ++i)
            if (pass == 1)
!                 /*
!                 ** Output an INT32_MIN "transition"
!                 ** if appropriate--see above.
!                 */
!                 puttzcode(((ats[i] < INT32_MIN) ?
!                     INT32_MIN : ats[i]), fp);
            else    puttzcode64(ats[i], fp);
        for (i = thistimei; i < thistimelim; ++i) {
            unsigned char    uc;
***************
*** 2176,2183 ****
            if (usestart) {
                addtt(starttime, type);
                usestart = FALSE;
!             } else if (stdoff != 0)
!                 addtt(min_time, type);
        } else for (year = min_year; year <= max_year; ++year) {
            if (useuntil && year > zp->z_untilrule.r_hiyear)
                break;
--- 2185,2191 ----
            if (usestart) {
                addtt(starttime, type);
                usestart = FALSE;
!             } else    addtt(min_time, type);
        } else for (year = min_year; year <= max_year; ++year) {
            if (useuntil && year > zp->z_untilrule.r_hiyear)
                break;