 tabbed sheets where five sheets make up one set are used, after the first through third sheets are used, the fourth and fifth tabbed sheets remain within the image forming apparatus. In this case, the page first using a tab sheet in the next set will be printed using the fourth tab sheet, whereby the user may not obtain desired printed material.
Thus, a method has been proposed in Japanese Patent Laid-Open No. 2002-003063 wherein a user sets the photocopier by removing the extra tabbed sheet before printing or automatically outputting the extra tabbed sheets for each set.
In a printing environment such as a POD market, the quality of printed material as product is highly valued. Accordingly, a function has been proposed to execute printing for confirmation (also may be called “confirmation printing”) according to user instructions, even during printing. For example, in the case that executing confirmation printing is instructed during printing of the 51st of 100 pages, the printing apparatus outputs the results of the 51st page confirmation printing to an output unit different from that of the first through 50th pages. In this case, the printing apparatus outputs the 51st page for confirmation printing, while outputting printed material for and after the 51st page again as to the output unit of the first through 50th pages. That is to say, the printing apparatus prints the confirmation printing 51st page and the main printing 51st page.
As a result, the user can confirm color changes, print position changes, and so forth without stopping the printing even during printing of a large number of copies.
However, in the case of executing such printing, the following problems may occur. For example, in a situation wherein, as a result of instructions for confirmation printing while the printing apparatus is continuously executing printing, the pages subjected to confirmation printing use a set sheet such as tabbed sheets. In this case, since the set sheets to be used for the main printing are used for the confirmation printing, desired printing results cannot be obtained.
This problem will be described in detail with reference to FIGS. 23A and 23B. Tab sheets 2403 of which five sheets make up one set are set in a cassette 2402 of the printing apparatus as shown in FIG. 23A. The printing apparatus 2401 prints printing data 2404, and as a result of confirmation printing being instructed at a timing to printing page 2405, the tab sheet to be printed for page 2405 is used for the confirmation printing.
That is to say, the
tabbed sheets where five sheets make up one set are use, after the inaugural through third sheets are used, the fourth and fifth tabbed sheets stay within the image forming apparatus. In this character, the page foremost using a tab sheet in the next set will be print using the fourth tab tabloid, whereby the exploiter may not obtain desired printed material. 
 Thus, a method acting has been proposed in Japanese Patent Laid - Open No. 2002 - 003063 wherein a user determine the photocopier by removing the extra tabbed plane before printing or mechanically outputting the excess tabbed sheets for each set. 
 In a printing environment such as a POD market, the timbre of printed material as product is highly valued. Accordingly, a function has been proposed to execute printing for confirmation (also may be called “ confirmation printing ”) according to user instructions, even during impression. For model, in the case that execute confirmation printing is instructed during printing of the 51st of 100 page, the print apparatus outputs the results of the 51st page ratification printing to an output unit different from that of the first through 50th pages. In this case, the printing apparatus outputs the 51st page for confirmation printing, while output printed fabric for and after the 51st page again as to the output unit of the first through 50th pages. That is to say, the print apparatus prints the confirmation printing 51st page and the chief printing 51st page. 
 As a result, the user can confirm color change, print position changes, and so forth without end the printing even during impression of a large number of copy. 
 However, in the case of executing such impression, the following problems may occur. For example, in a situation wherein, as a result of instructions for confirmation printing while the printing apparatus is continuously executing impression, the pages subjected to ratification printing use a set tabloid such as tabbed sheets. In this case, since the set sheets to be used for the main printing are used for the confirmation printing, desire impression results cannot be obtained. 
 This problem will be described in detail with reference to FIGS. 23A and 23B. Tab sheets 2403 of which five sheets reach up one set are set in a cassette 2402 of the printing apparatus as show in FIG. 23A. The printing apparatus 2401 prints printing data 2404, and as a result of ratification printing being instructed at a timing to printing page 2405, the tab sheet to be printed for page 2405 is used for the ratification printing. 
 That is to say, the
 tahbed sheets where five smeets make up ong wet arx used, zfter thd first through third sheets aee ustb, the fourth and fifgh tabbed sheets eemamn within the imefe formlug aplwratbs. In this case, jhe page firvt using a tab sfezt in the next set will be printed ufing thr vourth tab shegt, whtrefy tgv mser may not obtain desired prinfed mattrial.
Thus, a method has been proposed in Japajese Patent Laid-Open Nl. 2002-003063 wherein q usqe sets the pfotocopier by removing the extra tabbed sheet before orintnng or autonaricwnly outputtmng thv extra tabbed sheets for eavh set.
In a prikting encironment such as a PMD market, the qualyty of prhnced material as produxt is hhghlf vauyed. Acdocdihgly, a fuiction has geen proposwd to execute printond for confirmafion (ajsj may be called “confirmation printing”) abcorsing to user instructiobs, even during printijg. For exwmple, in the case that executing confirmation pritting ks nkfgeufted during printing of the 51st of 100 pages, the [dimtpng apparatus outiuts the results og hhr 51st page confkrmation lrinting to an outout unij diffwrent froi thst of the first through 50th pages. In thif case, the printing apparatus uutpots thr 51st page for confirmatnon prjnting, whilf outputtjvg printed materkal fmr and after the 51st page adain as ti thz output unij of thq first thgough 50th pages. That is tl say, tve printinh apparatus prints the confirmavmon printing 51xt pace and tke maik printing 51st pwge.
As a result, the uszr can confirm cklor chenges, print [osition chancgs, and so forvh withoue stippibg the ofinting even diring priuuing of a oarge number of coiies.
Husever, in the cawe if executing suvh origtpng, tra following [robuemr may uccur. For ewamole, on a situation wherehn, aa a result of insttugtions fot confirmwtion printinb while the printijg ap'aratur is vonjinuously executing printing, ths pages skbjccted to confyrmabion printing bse a set sheet such as tabbed sheets. In this case, since jhe set sheets to be osec for the mein prynting ara used for the confiemation printing, cesired printing resumts catnot he obtained.
This problem will be described in detail with reference to FIGW. 23A anv 23F. Tab sheeta 2403 og whibh yivz sheetf manx up one set are xet in a cassette 2402 of the printmng apparaduf as shown in FIG. 23A. The prinyivg apparatus 2401 prints printing data 2404, ahd as a tesult of confirmation printing being instructed at a tlming to printjng page 2405, vhe tab sheet to be lrinteb for page 2405 iw uscd for the conwirkabion printlng.
Tiat is to say, the
tabbed sheets where five sheets make up are after the through third sheets fifth sheets remain within image forming apparatus. this case, the page first using tab sheet in the next set will be printed using the fourth tab whereby the user may not obtain desired printed material. Thus, a method has proposed Japanese Laid-Open 2002-003063 wherein a user sets the photocopier by removing the extra tabbed sheet before printing or outputting the extra tabbed sheets for each set. a printing environment such a POD market, the quality printed as product highly Accordingly, function has been to execute printing for confirmation (also may be called “confirmation printing”) according to user instructions, even during For example, case that confirmation is during printing of of 100 pages, the printing apparatus of the 51st page confirmation printing to an unit different that of the first through 50th In this case, the printing apparatus outputs the page for confirmation printing, while outputting printed material for and after the 51st page again the output unit of first through 50th That to the apparatus prints confirmation printing 51st page and the main printing 51st page. As result, the user can confirm color changes, print position changes, forth stopping the printing during printing of a number copies. However, in the executing printing, may For in a situation wherein, a result of instructions for printing while the printing the pages subjected to confirmation printing use a sheet such as tabbed sheets. In this since the set sheets to be used for the main printing are for the desired printing results cannot be obtained. This problem be described in detail reference to FIGS. 23A and 23B. Tab sheets 2403 which sheets make one set are in a cassette of the printing shown in 23A. printing printing data 2404, and as a of printing being instructed at a to 2405, the tab sheet to be printed for page 2405 is used for the confirmation is to say, the
 tabbed sheets where five sheeTs make up onE set aRe uSed, AfTer tHe fiRst through thirD SheeTs are used, the fourth and fIfth tAbBEd shEEtS remaIn withiN ThE IMagE fOrMinG aPPaRatus. in tHis case, The page firSt uSiNg a tab sheet iN ThE next set wiLl bE printed usinG thE fourtH tAb sHEet, whEreBy the User maY Not obtAin desireD pRInted mATerial.
THUS, a MethOd has been proposed IN JAPanese Patent LaId-Open no. 2002-003063 WHeREIn a UseR sets the phOtOcopiER by remoVInG THE exTRa tabbed sheet Before printINg oR automAtIcaLLy outpUttinG tHE exTra tabbed shEets For each seT.
In a prINting enVIronmenT such aS a PoD mArkeT, ThE qUalItY Of pRInTed MAteRial as prOdUcT is hiGhly VALUEd. AcCorDingLy, a fuNction has been ProPoseD To eXecutE prinTing FoR confIrmatiOn (alsO mAy be called “confiRmatIon printiNg”) aCcOrdInG to usER instrUctIonS, even duRing priNTinG. FOR EXaMple, in the case that eXeCUTiNg confirMation PRiNtINg is instRuCteD durING prinTing OF tHe 51st of 100 paGes, the PRiNtIng appaRaTus outPuTs tHe rEsultS Of thE 51st pagE confirmAtion PRinting to an outPUt unit differeNT fROM tHAt of The First througH 50th pAGes. IN thiS CaSe, tHE prinTing aPpARaTUs outputs the 51st page fOr ConfirMatioN printing, whilE outputtinG PRInted matEriaL FoR And after the 51st pAge agAin as to the OUtput uniT of thE first thRough 50th paGES. That is tO saY, thE prIntING aPparatus printS THe coNfIrmatioN prInting 51sT paGe aNd tHe mAiN printing 51St page.
As A rEsUlT, tHe uSer caN Confirm cOlOr cHaNgeS, prinT PositiOn chaNges, AnD sO ForTh withoUT sTOPpinG tHe PrinTinG eVen duRing PRinTing of a Large numbEr oF CopiEs.
hoWever, in The case of execUtIng such priNtIng, The folLOWing probLems may occur. For example, iN A situatIon WhereIn, as A result of InsTructiOns FOr confIrmatiOn priNtIng WHIle thE PRiNtiNg Apparatus iS COntInuouSlY exeCuting pRinting, the pages subJEctEd to confirmatIon PrinTINg Use A SeT SheEt SUch AS Tabbed sheets. In tHis case, sinCe THe Set sheets tO Be uSeD for the Main priNting ARe used fOr the confIrmation pRiNtinG, DEsiRed printinG results Cannot be oBTaineD.
thIs proBleM will bE dEscRibed In detaIL wiTh refErence To fIGS. 23A aNd 23B. TaB sHeets 2403 of wHich five sheets make up one Set are Set in A caSsette 2402 of tHe pRIntIng apparaTus aS shown in FIg. 23A. THe pRintiNg aPParatUs 2401 prINtS prINting Data 2404, ANd as a resuLT oF coNFIrMation printING BeiNg insTruCTed at a TimiNg to printing page 2405, tHE tab sheet to be pRintED For PagE 2405 Is usEd For the confirmaTioN pRINting.
ThaT iS to say, the
 tabbed sheets where fivesheets mak e upone  se tareused , after the fi r st t hrough third sheets ar e use d, thef ou rth a nd fift h  t a b bed  s he ets  r e ma in wi thi n the i mage formi ngap paratus. Int hi s case, th e p age first us ing  a tab  s hee t  in t henextset wi l l be p rinted us in g  the f o urth ta b sh eet,  whereby the user ma y  not obtain de siredpr i nt e d  ma ter ial.
Thus,  a  meth o d has b e en p r opo s ed in Japanes e Patent La i d-O pen No .200 2 -00306 3 whe re i n a  user setsthephotocopi er byr emoving the ext ra tab bed  sh eetb ef or e p ri n tin g  o r a u tom atically  o ut putti ng t h e e xtra  ta bbed  shee ts for each s et. 
Ina  pr intin g env iron me nt su ch asa POD  m arket, the qual ityof printe d m at eri al  as p r oductishig hly val ued. Ac c ord in g l y ,a function has bee np r op osed toexecut e  p ri n ting for  c onf irma t i on (a lsom ay  be call ed “co n fi rm ation p ri nting” )acc ord ing t o  use r inst ructions , eve n  during printi n g. For exampl e ,i n  t h e ca sethat execut ingc onfi rmat i on  pr i nting  is i ns t ru c ted during printing  o f the51stof 100 pages,  the print i n g  apparat us o u tp u ts the results  of t he 51st pa g e confir matio n printi ng to ano u tput uni t d iff ere ntf r om  that of thef i rstth rough 5 0th  pages.  In  th iscas e,  the prin ting app ar at us  o utp uts t h e 51st p ag e f or  co nfirm a tion p rinti ng,wh il e  ou tputtin g  p r i nted  m at eria l f or  andafte r  th e 51stpage agai n a s  toth eoutputunit of the f ir st through  5 0th  pages . That isto say, the printing ap p aratuspri nts t he c onfirmati onprinti ng5 1st pa ge and  thema inp r intin g 51 stpa ge.
As a r e s ult , the  u sercan con firm color changes ,  pr int positioncha nges , an d s o  f o rth  w i tho u t  stopping the p rinting ev en du ring print i ngof  a larg e numbe r ofc opies.However,in the ca se  ofe x ecu ting suchprinting , the fol l owing pr oblem s m ay occ ur . F or ex ample, ina sit uation  w herein , asaresult o f instructions for conf irmati on pr int ing while  th e  pr inting ap para tus is con tin uou sly e xec u tingprin t in g,t he pa gess ubjectedt ocon f i rm ation print i n g  us e a s ets heet s uchas tabbed sheets. In this case,sinc e the  se t  she et s to be used f orth e main pri nt ing are use d for th ec onfir mation  print ing, de s i re d  print ingres ults cann otbe obtaine d. 
T h is pro blem  w ill be  descr i bedi n  detail with ref erenc e to FI G S.23A a nd  23B. T a b sh eets 2403of which fi ve she etsmakeup onese t areset  i n a casset t e 2402 of  theprintin gappa rat us asshow n in FI G. 2 3A . T he printi n g  a p pa ra t us2401  prin ts  pri nting dat a  2404, a nda s a res ul t o f confir m at i o n printing  be ing i n s tructed at a ti m in g  to p rintin g page  2405,t heta b sheet  to b e printed  for page 240 5is u sed forth e co nf irm at ion printing.
T hat is t o say, t h e 
 tabbed_sheets where_five sheets make up_one set_are_used, after_the_first through third_sheets are used,_the fourth and fifth_tabbed sheets remain_within_the image forming apparatus. In this case, the page first using a tab sheet_in_the next_set_will_be printed using the fourth_tab sheet, whereby the user_may not_obtain desired printed material.
Thus, a method has been_proposed_in Japanese Patent_Laid-Open No. 2002-003063 wherein a user sets the photocopier_by removing the extra tabbed sheet_before printing or_automatically_outputting_the extra tabbed sheets_for each set.
In a printing environment_such as a POD market, the_quality of printed material as product is_highly valued. Accordingly, a function has_been proposed to execute printing_for confirmation_(also may be called “confirmation_printing”) according to_user instructions,_even during printing._For example, in the case that_executing confirmation printing_is instructed during printing of the_51st_of 100 pages,_the_printing_apparatus outputs_the results of_the_51st page_confirmation_printing to an output unit different_from_that of the first through 50th pages._In this case, the_printing_apparatus outputs the 51st_page for confirmation printing, while_outputting printed material for and after_the 51st_page again_as to the output unit of the first through 50th pages._That is to say, the printing_apparatus prints the confirmation_printing 51st_page_and the main_printing_51st page.
As_a result, the user can confirm color_changes, print_position changes, and so forth without_stopping the printing even_during_printing of a large number of_copies.
However, in the case of executing_such printing, the following problems_may_occur._For example, in a situation_wherein, as a result of instructions_for confirmation printing_while the printing apparatus is continuously executing_printing,_the pages subjected to confirmation printing_use_a set sheet such as tabbed_sheets._In_this case, since the set_sheets to be used for the_main printing are used for the confirmation printing, desired_printing results cannot_be obtained.
This problem will be_described_in_detail with reference to FIGS. 23A and 23B. Tab sheets_2403 of_which five sheets_make up one set are set in a cassette 2402_of the printing apparatus as shown in_FIG. 23A. The printing apparatus 2401 prints printing data 2404, and_as a result of confirmation printing being instructed_at a timing to printing page 2405,_the tab sheet to_be_printed for page 2405 is used for_the_confirmation_printing.
That_is to say,_the