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DataTypes Comments Section 4

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4 Basic Types

  • 4.1 Binary Data (BIN) specializes LIST<BN>
    1. "a character-based ITS SHOULD NOT convert character data into arbitrary binary data and then represent binary data in a character encoding." - what does this mean? Maybe an example is called for?
  • 4.2 Encapsulated Data (ED) specializes ANY
    1. "Note that ST is a specialization of ED where the mediaType is fixed to text/plain and several other properties are constrained to null." - this seems oddly out of place...
    2. data - "Operations may be performed directly upon the binary content by using data." - I'm not sure what sort of operations are being suggested, but here is a place where it needs to be stressed that content is identity. If you alter the content of the data portion of an ED, (assuming I understand the section on identity correctly), you have a different ED.
    3. reference -
      • Type: TEL.URL - "A telecommunication address (TEL), such as a URL... - isn't it more than such as the definition says that it is.
      • "... a URL for HTTP or FTP" - I'm not sure what a URL for HTTP would look like. I would propose the following: "A URL that resolves to binary content of the ED." (I don't get "that could as well have been...")
    4. integrityCheck - "The integrity check is a shortA binary value containing a cryptographically strongsome form of a checksum that iscalculated over the data." - It doesn't have to be "cryptographically strong", whatever that means, or be calculated of strictly binary data. "Short" is a strictly subjective term and has no meaning...
    5. translation - "Translations SHALL not contain translations." - is this stated verbally to keep from having to come up with a specialized, non-translated ED?
    6. 4.2.1 P1 - ED acts as a wrapper of binary content content - ???
    7. Definition 105 is curious, especially as the sentence following it appears to contradict it. It would seem that either (a) the reference is opaque (e.g. an ITS issue) and the ED always returns data of (b) the reference is visible and the retrieval of the actual information is done by the client application. I don't understand the situation described here.
    8. Table 14 - heading is messily rendered.
    9. Tables of recommended media types - especially based on someone's determination of the relative security and ability to propagate viruses seems to be pushing the "abstract" nature of this spec...
    10. "There is a risk that general SGML/XML is too powerful to allow a sharing of general SGML/XML documents between different applications. " - gosh, then what is HL7 going to use instead?
    11. What are the invariants with respect to binary compliance to the media type. If, for instance, an XML document isn't well formed, is there anything that needs to be said or done?
    12. Table 15 - heading is messily rendered.
    13. 4.2.6 Reference Definition: "A telecommunication address (TEL), such as a URL for HTTP or FTP, which will resolve to precisely the same binary data that could as well have been provided as inline data." (See comment on this topic above.
    14. The reference SHALL point to the same data as provided inline. It is an error if the data resolved through the reference does not match either the integrity check, in-line data, or data that had earlier been retrieved through the reference and then cached. - this seems like a strange statement. The intent is to say that it cannot change, but this is a curious way to go about it. If we didn't cache it, then is change ok?
    15. It still isn't clear whether it is the obligation of the data type ITS or the retrieving application to dereference the URL.
    16. 4.2.7 Integrity check. - issues with the definition are discussed earlier in this document.
    17. Is Integrity Check strictly for reference resolution, or does it apply to "inline" data as well?
    18. Are sha-1 and sha-256 the only algorithms that can be used? If so, I withdraw the suggested changes to the definition above...
    19. 4.2.9 - (formatting) - bumps into the preceding table, which is confusing.
    20. 4.2.12 - length - are there only two "kinds" of item in the content - characters and bits? If so, this needs to be simplified. If not, it needs to tell me where to find what a "kind" is and get the unit length. Until I read that images had a binary length, I was assuming that the length would either be "1" (for 1 picture) or the number of frames.
    21. nonNull ED SHALL always have some valid content, and length is greater than 0. - "valid" is an interesting statement, but the question remains - does data have to be non-null, even when reference isn't?
    22. Not that I want to really see it, but why no DTDL for SubPart? and equal?
  • 4.3 Character String (ST) specializes ED
    1. ST is primarily intended for machine processing? Where do we put text intended to be read by people???
    2. What does "the appearance of text does not bear meaning" mean? Is appearence the keyword or are we genuinely asserting that you can only use ST for meaningless text? Is "formalized text" (whatever that is) or "all kinds of names" meaningless text?
    3. "It SHALL be contained in-line - the ED.reference property cannot be used." - these SHALLs and SHALL NOT's seem extraneous in most cases. Wouldn't it be sufficient to say that ST SHALL comply with all invariants and be done with it?
  • 4.4 Character String with Code (SC) specializes ST
    1. "The original text of the code, if provided, is the content of the string." - these sort of statements (especially the footnote) are a bit confusing. As this is an abstract specification, it seems like its primary job is to indicate what various predicates and properties do, not what does or does not get sent over the wire. Thus, if provided makes no sense. Does code.originalText return a value or does it not? Why, if the string is required, would you want to make originalText optional?
  • 4.5 Concept Descriptor (CD) specializes ANY
    1. P2 - the last sentence of this paragraph, starting with "If the concept (the intent of the original text) ..." needs to be moved further down in the description. These first few paragraphs need to be descriptive if the reader is going to amek it through this.
    2. P5 - Attributes with type CD are generally bound to a domain that constrains the coded concepts to which a CD may refer. - What does "bound" mean in this context?
    3. P5 - "The binding process is discussed in depth [[here]]." - where is here?
    4. P5 - again, the SHALL's need to be moved further down. The reader is still trying to figure out what this thing is all about and this sort of declarations don't help.
    5. code - shouldn't this be constrained further than ST.SIMPLE (or should ST.SIMPLE be further constrained?) - I don't believe that character sets or translations have any place here
    6. valuesetVersion - is datetime really the correct data type for this? If so, why isn't codeSystemVersion the same type?
    7. Is "root concept" defined anywhere?
    8. isCompositional - how can a code refer directly to two concepts in a coding system?
    9. 4.5.2 P2 - A CD that has a code attributes SHALL...
    10. 4.5.4 P2 "HL7 SHALL specify how these version strings are formed for each external code system. If HL7 has not specified how version strings are formed for a particular coding system, version designations have no defined meaning for such coding system." - This is a tall order. When SHALL HL7 start on this task? If they don't do it, are they declared out of compliance?
    11. 4.5.5 P2 - "Applications SHALL NOT reject an instance because of the presence or absence of any or a particular value set." - Not sure what this means - is it talking about the value set property, or the value set itself? If it is the latter case, how can it be absent?
    12. 4.5.6 P1 - "valueSetVersion SHALL be provided when a valueSet is provided, and otherwise SHALL be null. The value set version specifies a date, with the resolution of a particular second. The date is the date/time that the value set being used was published." - surprisingly strong requirement. Is this information available currently? Is there any way to get around it if you simply don't know?
    13. 4.5.9 - table 21 is kind of messed up.
    14. 4.5.9 - just a question - since the possible options are "none, O, OP, R and OR", wouldn't it be simpler to make it a simple CS?
    15. 4.5.11 - Source - Can a source have translations? In general, this seems to be opening a can of worms, as it looks like it is really intended to be a reference rather than its own value, but there is nothing in the specification that prevents it from being a separate thing - especially as most of the information in a CD (especially translations!) don't play a role in the identity of the CD itself!
    16. 4.5.12 - we need examples. Lots of examples - this just doesn't make sense as it sits...
    17. 4.5.13 last paragraph - "HL7 SHALL make a ruling about which is the preferred form. HL7 SHALL " - I just don't think specifications can do this. Compliant applications SHOULD and SHALL - you can't rule HL7 as non-compliant!
    18. - "that is found to the full Snomed-CT valueset" (found in?)
    19. - "he OIDs used in these examples that in the OID space 2.16.840.1.113883.6, 2.16.840.1.113883.5 and 2.16.840.1.113883.11 are the correct OIDs to use in production instances." - why wouldn't you just use the correct ones when the exist?
    20. Examples - <translation id="s1" code="burn" - I don't see any documentation that allows an id field in translation. What gives?
  • 4.6 Coded Ordinal (CO) specializes CD
  • 4.7 Coded Simple Value (CS) specializes CV
  • 4.8 Unique Identifier String (UID) specializes ST.SIMPLE
  • 4.9 ISO Object Identifier (OID) specializes UID
  • 4.10 DCE Universal Unique Identifier (UUID) specializes UID
  • 4.11 HL7 Reserved Identifier Scheme (RUID) specializes UID
  • 4.12 Instance Identifier (II) specializes ANY
  • 4.13 Universal Resource Locator (URL) specializes ANY
  • 4.14 Telecommunication Address (TEL) specializes URL
  • 4.15 Address Part (ADXP) specializes SC.NT
  • 4.16 Postal Address (AD) specializes LIST<ADXP>
  • 4.17 Entity Name Part (ENXP) specializes SC.NT
  • 4.18 Entity Name (EN) specializes LIST<ENXP>