Automating, enhancing, and improving eRegulations

Regulation Z (Truth in Lending) is now hosted on eRegulations – CFPB’s platform to make regulations easier to find, read, and understand. This regulation follows approximately six months since the last regulation (Regulation E – Electronic Fund Transfers) was first hosted. That’s admittedly a long time for what seems like a simple content update. However, Regulation Z differs significantly from Regulation E, requiring us to improve and update the eRegulations platform. eRegulations now handles longer regulations gracefully, and these updates also make it significantly easier to host additional regulations going forward. Here, we’ll share some of the more interesting improvements and in the process also reveal more about how our platform works.

Hosting larger regulations

The first and foremost difference between the two regulations is that Regulation Z is significantly larger than Regulation E in almost all aspects. In Table 1, you can see the difference between Regulation E and Regulation Z for each type of content. For example, Regulation E has 26 sections while Regulation Z has 54.

  Regulation E Regulation Z
Subparts 2 7
Sections 26 54
Appendices 2 15

Table 1: The number of each type of content per regulation.

Regulation E is 1.5 MB on disk, while Regulation Z is almost ten times larger at 11 MB, when both texts are represented as a pretty-printed JSON trees (not including images). That’s a lot of text; in comparison, War and Peace by Leo Tolstoy is 3.1 MB. The fact that Regulation Z is a significantly longer regulation than Regulation E drove how we approached the updates and improvements to the tool – from the need to automatically retrieve content changes, to allowing additional types of appendices, to separating the supplement into more manageable chunks.

Compiling regulations

A primary feature of eRegulations is the ability to view past, current, and future versions of a regulation. Previously, the source content that was fed to the parser to generate each version was created manually. The most significant change we made over the past six months was to automate this process.

Each version of a regulation consists of a series of Federal Register (FR) final rule notices applied to the previous version of the regulation. Each notice describes changes to individual paragraphs of the regulation (think of it like a diff). A change can add, revise, delete, or move a paragraph and looks something like this:

  1. Section 1026.32 is amended by:
  2. Revising paragraph (a)(2)(iii)
  3. The revisions read as follows:
  4. (a) ***
  5. (2) ***
  6. (iii) A transaction originated by a Housing Finance Agency, where the Housing Finance Agency is the creditor for the transaction; or

This example is from

Lines 1 and 2 describe which paragraph has changed, and how it has changed (known as the amendatory instructions). Line 6 shows you how paragraph 1026.36 (a)(2)(iii) reads after the revision. A notice can contain multiples of these changes.

Each version of a regulation on our platform is represented on the back end as a data structure (more specifically an ordered n-ary tree) that represents the entire regulation at that point in time. For each version of Regulation E, we manually read each FR notice and meticulously compiled plaintext versions that were fed to our parser to generate the tree structure. This was possible since in Regulation E we have three versions consisting of eight FR notices. Regulation Z, on the other hand, has 12 versions and 23 notices. Manual compilation of versions would be inefficient and more prone to error. It also is not a sustainable solution going forward. We wanted to be able to simply start the parser when the next Regulation E or Z notice was published – without having to manually apply the changes from the new notice.

We now automatically compile regulation versions. Each FR notice is processed by parsing the amendatory instructions (what has changed) and the actual changes (how it has changed), matching those up, and compiling the changes into a new version. Each FR notice has a corresponding XML representation – this also drove the conversion of our parser from being text-based to XML-based. This resulted in a far more sustainable application requiring less manual intervention to add an additional regulation.

Splitting and cleaning Federal Register notices

An individual regulation paragraph can change in a limited number of ways. A paragraph can be added, revised, moved, or deleted. Usually, these changes are written with reasonably consistent phrasing – making parsing them tractable. However, sometimes there are exceptions when the change is not expressed as clearly as possible. Adding rules to the code for these exceptions would have diminishing returns in the sense that the effort of getting the code correct, tested and ensuring that it doesn’t break any of the other parsing, would far outweigh the benefits of the unique rule. To handle those special cases, we built a mechanism to allow us to keep local copies of the XML notices taken from the Federal Register and make changes to that copy to make it easier to parser. The parser looks first in our local repository of notices to see if a copy of a required notice exists, before downloading it from the Federal Register. This enabled us to gracefully handle phrases that aren’t used frequently enough to warrant their own custom rule.

The same mechanism came in handy when we discovered that several notices for Regulation Z had more than one effective date. Notices with the same effective date are what comprise a version of a regulation. The following example illustrates how complicated this can get:

This final rule is effective January 10, 2014, except for the amendments to §§ 1026.35(b)(2)(iii), 1026.36(a), (b), and (j), and commentary to §§ 1026.25(c)(2), 1026.35, and 1026.36(a), (b), (d), and (f) in Supp. I to part 1026, which are effective January 1, 2014, and the amendments to commentary to § 1002.14(b)(3) in Supplement I to part 1002, which are effective January 18,


In these cases, we manually split up the notices, creating a new XML source document for each effective date. This was another situation in which a manual override made the most sense given time and effort constraints.

Improving appendices

The types of information the appendices for Regulation Z contain are far more varied than those for Regulation E. First, the structure of the text in the appendices for Regulation Z differs from that of Regulation E. This required a complete re-write of the appendix parsing code to allow for the new format. Secondly, the appendices for Regulation Z contain equations, tables, SAS code, and many images. Each of those presented unique challenges. To handle tables we had to parse the XML that exhaustively represented the tables into something meaningful and concise, and then display that in visually pleasing HTML tables. The SAS code was handled by the same mechanism.

Some of the appendices in Regulation Z contain many images. To speed up page loads for those sections we re-saved all of the images using image formats that compress the content with minimal quality degradation and introduced thumbnails. Clicking on the thumbnail brings the user to the larger image, but the thumbnails ensure that pages load faster. We also lazy-load the images on scroll to speed up the initial page load. Regulation Z, in its original form, also contains a number of appendices where the images contain text. We pulled the text out of those images, so that the text is now searchable and linkable providing for a better user experience. With the exception of compiling regulations, most of the changes we made for Regulation Z were directly a result of that fact that Regulation Z is longer.

Breaking up the supplement

Supplement I is the part of the regulation that contains the official interpretations to the regulation. Loading Supplement I as a single page worked well for Regulation E (where the content is relatively short) but with Regulation Z this led to a degraded experience as the supplement is significantly longer. We split Supplement I, so it could be displayed a subpart at a time. Displaying the interpretations a subpart at a time was considered a more cohesive experience by our product owner (rather than breaking Supplement I to be read a section at a time). Our code was previously written with the intent of displaying a section at a time (with the entirety of Supplement I considered as a section). This worked nicely because that also reflects how the data that drives everything is represented. With the Supplement displayed a subpart at a time, there is no corresponding underlying data structure that tells us that the following sections of Supplement I should be collected and displayed together. This required a rewrite of some of our display logic. Supplement I is now easier to read as a result.


We made many other changes to the eRegulations tool along the way: introducing a landing page for all the regulations, extending the logic to identify defined terms with the regulation, and based on user feedback – introducing help text to the application. Each one of those represents a significant effort, but here we wanted to explain some of the larger efforts. All our code is open source, so you can see what we’ve been up to in excruciating detail (and suggest changes).

Through this set of changes, we’ve hopefully made it easier to navigate, understand, and comply with Regulation Z. Going forward it will also be easier to add future regulations and deal with longer regulations.