==法律法规==
法律自然就是 《 移民法 》 ， 法规指的是 美国联邦法规 即 [https://www.lawuscis.cornell.edugov/cfr/textlaws-and-policy/22legislation/partimmigration-42/subpartand-F 22 CFR Chapter I, Subchapter E, Part 42, Subpart F nationality- Numerical Controls act Immigration and Priority DatesNationality Act]， 这是对移民 收录于联邦 法 的要求的具体实施。可以看到，除了2013年加了一段”Entitlement to immigrant classification”以外，对应法规全部都是90年代的产物，近20年没有更新过。典（United States Code, USC）第8卷
===§42排期对应的法规是《美国联邦法规》第22卷第1章第E分章第42部第F分部 [https://www.51 Department control of numerical limitationslaw.===(a) ''Centralized controlcornell.'' Centralized control of the numerical limitations on immigration specified in INA 201edu/cfr/text/22/part-42/subpart-F 22 CFR Chapter I, Subchapter E, 202Part 42, Subpart F - Numerical Controls and 203 is established in the Department. The Department shall limit the number of immigrant visas that may be issued and the number of adjustments of status that may be granted to aliens subject to these numerical limitations to a number:Priority Dates] 联邦法规是政府部门的操作指南。在三权分立的美国架构下，国会负责立法，行政部门根据法律制定法规。这些法规可以看作是对联邦法律的具体实施细则。
(1) Not to exceed 27 percent of the world-wide total made available under INA 203 (a), (b) and (c) in any of the first three quarters of any fiscal year; and (2) Not to exceed, in any month of a fiscal year, 10% of the world-wide total made available under INA 203 (a), (b) and (c) plus any balance remaining from authorizations for preceding months in the same fiscal year. (b) ''Allocation of numbers.'' Within the foregoing limitations, the Department shall allocate immigrant visa numbers for use in connection with the issuance of immigrant visas and adjustments based on the chronological order of the priority dates of visa applicants classified under INA 203 (a) and (b) reported by consular officers pursuant to §42.55(b) and of applicants for adjustment of status as reported by officers of the DHS, taking into account the requirements of INA 202(e) in such allocations. In the case of applicants under INA 203(c), visa numbers shall be allocated within the limitation for each specified geographical region in the random order determined in accordance with sec. 42.33(c) of this part. (c) ''Recaptured visa numbers.'' An immigrant visa number shall be returned 可以看到，除了2013年加了一段”Entitlement to the Department for reallocation within the fiscal year in which the visa was issued when: (1) An immigrant having an immigrant visa is excluded from the United States and deported; (2) An immigrant does not apply for admission to the United States before the expiration of the validity of the visa; (3) An alien having a preference immigrant visa is found not to be a preference immigrant; or (4) An immigrant visa is revoked pursuant to §42.82. [56 FR 51174, Oct. 10, 1991, as amended at 59 FR 15302, Mar. 31, 1994; 63 FR 48578, Sept. 11, 1998] ===§42.52 Post records of visa applications.===(a) ''Waiting list.'' Records of individual visa applicants entitled to an immigrant classification and their priority dates shall be maintained at posts at which immigrant visas are issued. These records shall indicate the chronological and preferential order in which consideration may be given to immigrant visa applications within the several immigrant classifications subject to the numerical limitations specified in INA 201, 202, and 203. Similar records shall be kept for the classes specified in INA 201(b)(2) and 101(a)(27) (A) and (B) which are not subject to numerical limitations. The records which pertain to applicants subject to numerical limitations constitute “waiting lists ” within the meaning of INA 203(e)(3) as redesignated by the Immigration Act of 1990. (b) ''Entitlement to immigrant classification.'' An alien shall be entitled to immigrant classification if the alien: (1) Is the beneficiary of an approved petition according immediate relative or preference status; (2) Has satisfied the consular officer that the alien is entitled to special immigrant status under INA(101)(a)(27) (A) or (B); (3) Is entitled to status as a Vietnam Amerasian under section 584(b)(1) of section 101(e) of Public Law 100-202 as amended by Public Law 101-167 and re-amended by Public Law 101-513; or (4) Beginning in FY-95, is entitled to status as a diversity immigrant under INA 203(c). (c) ''Record made when entitlement to immigrant classification is established.'' (1) A record that an alien is entitled to an immigrant visa classification shall be made whenever the consular officer is satisfied—or receives evidence—that the alien is within the criteria set forth in paragraph (b) of this section. (2) A separate record shall be made of family members entitled to derivative immigrant status whenever the consular officer determines that a spouse or child is chargeable to a different foreign state or other numerical limitation than the principal alien. The provisions of INA 202(b) are to be applied as appropriate when either the spouse or parent is reached on the waiting list. (3) A separate record shall be made of a spouse or child entitled to derivative immigrant status whenever the consular officer determines that the principal alien intends to precede the family. [56 FR 51174, Oct. 9, 1991, as amended at 61 FR 1836, Jan. 24, 1996; 78 FR 31399, May 24, 2013] ===§42.53 Priority date of individual applicants.===(a) ''Preference applicant.'' The priority date of a preference visa applicant under INA 203 (a) or (b) shall be the filng date of the approved petition that accorded preference status. (b) ''Former Western Hemisphere applicant with priority date prior to January 1, 1977.'' Notwithstanding the provisions of paragraph (a) of this section, an alien who, prior to January 1, 1977, was subject to the numerical limitation specified in section 21(e) of the Act of October 3, 1965, and who was registered as a Western Hemisphere immigrant with a priority date prior to January 1, 1977, shall retain that priority date as a preference immigrant upon approval of a petition according status under INA 203 (a) or (b). (c) ''Derivative priority date for spouse or child of principal alien.'' A spouse or child of a principal alien acquired prior to the principal alien's admission shall be entitled to the priority date of the principal alien, whether or not named in the immigrant visa application of the principal alien. A child born of a marriage which existed at the time of a principal alien's admission to the United States is considered to have been acquired prior to the principal alien's admission. ===§42.54 Order of consideration.===(a) ''General.'' Consular officers shall request applicants to take the steps necessary to meet the requirements of INA 222(b) in order to apply formally for a visa as follows: (1) In the chronological order of the priority dates of all applicants within each of the immigrant classifications specified in INA 203 (a) and (b); and (2) In the random order established by the Secretary of State for each region for the fiscal year for applicants entitled to status under INA 203(c). (b) [Reserved] [56 FR 51174, Oct. 10, 1991, as amended at 59 FR 15302, Mar. 31, 1994; 61 FR 1836, Jan. 24, 1996; 63 FR 48578, Sept. 11, 1998] ===§42.55 Reports on numbers and priority dates of applications on record.===(a) Consular officers shall report periodically, as the Department may direct, the number and priority dates of all applicants subject to the numerical limitations prescribed in INA 201, 202, and 203 whose immigrant visa applications have been recorded in accordance with §42.52(c). (b) ''Documentarily qualified applicants.'' Consular officers shall also report periodically, as the Department may direct, the number and priority dates of all applicants described in paragraph (a) of this section who have informed the consular office that they have obtained the documents required under INA 222(b), for whom the necessary clearance procedures have been completed. [56 FR 51174, Oct. 10, 1991, as amended at 61 FR 1836, Jan. 24, 1996]以外，对应法规全部都是90年代的产物，近20年没有更新过。
==排期表的制定==
国务院（Department of State, DOS）对外发布的 [https://travel.state.gov/content/dam/visas/Statistics/Immigrant-Statistics/Immigrant%20Visa%20Control%20System_operation%20of.pdf The Operation of the Immigrant Numerical Control System] 一文，描述了排期表的指定方法
* 每月初，所有海外使领馆上报 documentarily qualified （中文称“审结”）的人员列表。信息只有 国家、类别、PD，不包含姓名等个人信息。本信息在每月的第一周计算* Visa Office (VO) 按月分配名额，结合上报的审结列表，划定排期的日期。其中，会考虑如下因素：** 以往的名额使用情况** 预测下月的名额使用情况和退回情况** 预测的 USCIS 使用情况（这是个神坑）* 综合考虑以上因素以后，如果名额有多余，那就是 C。如果名额不够，那就以最后一个'''排不到'''的人的排期日划线* 排期以周为组，每月的1-7日为1组，8-14日，5-21日，以及22日以后。所以排期的日期永远是1/8/15/22中的一个* VO计算好排期以后，会发布给各驻海外使领馆、移民局，并公布在 Consular Affairs (CA) 的网站上 travel.state.gov* 名额分配：** 使领馆名额，因为有上报时已经有个人信息，一旦排期计算完毕，名额即分配到个人** USCIS 等到所有处理完毕，发卡之前，才会申请名额（坑 x 2）
== USCIS和排期表 ==
不管是从联邦法规，还是排期表的制定流程，都可以看到：全程不需要 USCIS 提供任何数据，也不需要他们参与任何决策。
USCIS唯一的责任就是：批卡的时候，向 USCIS 申请一下名额。
== AB表 ==
因为 USCIS 的流程和数据完全不透明，在2015年，引入了 A B 表的制度，其本意是为了让 USCIS 的流程更接近 DOS 的，也就是先按照一定的提前量收表（B表），这样可以准确知道 I-485 库存的 国家 和 Priority Date，以此可以让排期更准确。
在初次实施 AB表 的 2015年10月 排期，国务院在9月初公布的 B表 日期，比 A表 大幅提前，让很多人开始准备在新财年交表。但在9月25日，财年开始前5天，国务院突然修改了排期表，大幅退后了 B表 排期。
* EB-2 印度，退后2年，2011-07-01 退到 2009-07-01* EB-2 中国，退后17个月，2014-05-01 退到 2013-01-01* EB-3 菲律宾，退后5年，2015-01-01 退到 2010-01-01
这一事件引发了所谓 Visagate，或者“签证门”诉讼。诉讼的结果是，法院判决，排期表在下月生效以前，不能认为是最终版。国务院有权在生效前做出改变。<blockquote>The two Visa Bulletins are not "definitive statements" but informative statements; the September 9, 2015, Visa Bulletin did appear to have a direct and immediate effect on the day-to-day business of Plaintiffs; the Visa Bulletins did not have the status of law, if at all, until October 1, 2015; immediate compliance with the terms of these Visa Bulletins was clearly not expected; and the Visa Bulletins did not necessarily answer a legal question. These indicia of finality support the Court's conclusion that the two Visa Bulletins in question do not constitute final agency action.</blockquote>随着第一次引入 AB表 导致的闹剧，USCIS 在随后并没有一直使用 B表。在 2017年1月 更换总统以后，更出现了2018财年全年不适用 B表 的情况。这个半吊子的项目，目前只剩下了仍然在 DOS 网站挂着的那句“USCIS, in coordination with Department of State (DOS), is revising the procedures for determining visa availability for applicants waiting to file for employment-based or family-sponsored preference adjustment of status. The revised process will better align with procedures DOS uses for foreign nationals who seek to become U.S. permanent residents by applying for immigrant visas at U.S. consulates and embassies abroad.”
至于什么时候 USCIS 能 better align with DOS，就只有天知道了