The tdate is the day-of-year dot the-year, with the day of year expressed in base 7. By day-of-year, I mean how many days it has been since the previous year. For example, today is 62.2012. If it were January 1st, it would be 1.2012. If it were February 1st, it would be 44.2012. Notice that 44 is just base-7 for 32 (the 32nd day of the year). There are two advantages to using this format: First, you can forget about months altogether. Admit it, they're a silly idea. Second, you always know what day of the week it is. That is, for any tdate within this year, you can just use the last digit to figure out exactly which day of the week it is. Thirdly, when you tell other people that you insist on using tdate's, they get a very funny look on their face. It's totally worth it. (Here is a printable version of this year's tdate calendar. I recommend printing in landscape (sideways) mode.) Show the tdate calendar for: tdate calendar for the year 2012: Sun Mon Tue Wed Thu Fri Sat Sun Mon Tue Wed Thu Fri Sat Sun Mon Tue Wed Thu Fri Sat Jan 1 2 3 4 5 6 10 11 12 13 14 15 16 20 21 22 23 24 25 26 30 31 32 33 34 35 36 40 41 42 43 Feb 44 45 46 50 51 52 53 54 55 56 60 61 62 63 64 65 66 100 101 102 103 104 105 106 110 111 112 113 114 Mar 115 116 120 121 122 123 124 125 126 130 131 132 133 134 135 136 140 141 142 143 144 145 146 150 151 152 153 154 155 156 160 Apr 161 162 163 164 165 166 200 201 202 203 204 205 206 210 211 212 213 214 215 216 220 221 222 223 224 225 226 230 231 232 May 233 234 235 236 240 241 242 243 244 245 246 250 251 252 253 254 255 256 260 261 262 263 264 265 266 300 301 302 303 304 305 Jun 306 310 311 312 313 314 315 316 320 321 322 323 324 325 326 330 331 332 333 334 335 336 340 341 342 343 344 345 346 350 Jul 351 352 353 354 355 356 360 361 362 363 364 365 366 400 401 402 403 404 405 406 410 411 412 413 414 415 416 420 421 422 423 Aug 424 425 426 430 431 432 433 434 435 436 440 441 442 443 444 445 446 450 451 452 453 454 455 456 460 461 462 463 464 465 466 Sep 500 501 502 503 504 505 506 510 511 512 513 514 515 516 520 521 522 523 524 525 526 530 531 532 533 534 535 536 540 541 Oct 542 543 544 545 546 550 551 552 553 554 555 556 560 561 562 563 564 565 566 600 601 602 603 604 605 606 610 611 612 613 614 Nov 615 616 620 621 622 623 624 625 626 630 631 632 633 634 635 636 640 641 642 643 644 645 646 650 651 652 653 654 655 656 Dec 660 661 662 663 664 665 666 1000 1001 1002 1003 1004 1005 1006 1010 1011 1012 1013 1014 1015 1016 1020 1021 1022 1023 1024 1025 1026 1030 1031 1032 Key today weekend bold means the day-of-month is 10, 20, or 30