14 CFR XML File Structure

[MichaelDMcCracken]

@ryanburnette We will keep a detailed log of the structure of the XML files here for the purpose of accessing particular regs.

CFRDOC

x = Aviation14CFR.data
x.children[1].children[5] => TITLE
x.children[1].children[5].children[7] => CHAPTER (contains all the relevant regs)

CHAPTER

Below the CHAPTER heading, the file contains a Table of Contents and the individual subchapters for that chapter. In Title 14, Chapter I is divided into Volumes 1 - 3 that correspond to each file that we have downloaded.

x.children[1].children[5].children[7].children[1]

• Returns TOC
• Table of Contents for the entire CHAPTER

x.children[1].children[5].children[7].children[x]

• Returns SUBCHAP
• Contains individual parts pertaining to that subchapter
• x can be any odd integer above 1, up to the number of subchapters contained in that volume plus 4

Example: Volume 1 contains 3x SUBCHAP. Therefore, each SUBCHAP can be accessed with values of 3, 5, and 7 for x

SUBCHAP

Where x pertains to the desired SUBCHAP...

x.children[1].children[5].children[7].children[x].children[3]

• Returns HD
• Contains the SUBCHAP name

PART

x.children[1].children[5].children[7].children[x].children[y]

• Returns PART
• Contains SUBPART (where applicable) or SECTION
• y must be an odd integer above 5 but no greater than the number of SUBCHAP (if applicable) or SECTION plus 6 (don't hold me to that, yet)

x.children[1].children[5].children[7].children[x].children[y].children[5]

• Returns CONTENTS
• Basically a list of all SECTION for that given PART

SUBPART

x.children[1].children[5].children[7].children[x].children[y]

SECTION

If no SUBPART exists, the following will open to a specific SECTION

x.children[1].children[5].children[7].children[x].children[y]

Example to find 14 CFR 3.5

x.children[1] => CFRDOC
x.children[1].children[5] => TITLE
x.children[1].children[5].children[7] => CHAPTER => Chapter I, FAA, DOT
x.children[1].children[5].children[7].children[3] =>SUBCHAP => Subchapter A - Definitions and General Requirements
x.children[1].children[5].children[7].children[3].children[7] => PART => Part 3 - General Requirements
x.children[1].children[5].children[7].children[3].children[7].children[13] => SECTION => § 3.5
x.children[1].children[5].children[7].children[3].children[7].children[13].children[7] => P
x.children[1].children[5].children[7].children[3].children[7].children[13].children[7].children[2]

Example to Find 14 CFR 3.5

x.xpath("/CFRDOC/TITLE/CHAPTER/SUBCHAP[1]/PART[2]/SECTION[2]/P[2]").text =>

"\n        Airworthy means the aircraft conforms to its type design and is ..."

It appears that the xpath above still contains children. Child[0] contains the "\n " while [1] and [2] actually contain the text we desire. My guess is that this is due to formatting requirements on the ecfr.gov website specifically for definitions. Only time will tell, but I do not think that every reg will have this. And even if it does, I don't necessarily think there's anything wrong with keeping the format to match.

We can also run .length on the xpath request to determine if a given request will return empty or not.

Notes

1. The even numbered children always (in every case I can find, at least) contain a string that just adds a line break.
2. It appears that the .children[0] usually returns the text within a tag

[ryanburnette]

Try running .path on any of these paths. For example:

Aviation14CFR.data.children[1].children[5].children[7].path
=> "/CFRDOC/TITLE/CHAPTER"

So that's the same as ...

Aviation14CFR.data.xpath("/CFRDOC/TITLE/CHAPTER")

[ryanburnette]

Aviation14CFR.data.children[1].children[5].children[7].children[3].children[7].children[13].children[7].path
=> "/CFRDOC/TITLE/CHAPTER/SUBCHAP[1]/PART[2]/SECTION[2]/P[2]"