Content for  TR 21.801  Word version:  17.0.0

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5  Structure

5.1  Subdivision of the subject matter

5.1.1  General

3GPP TSs or 3GPP TRs are so diverse that no universally acceptable rules can be established for the subdivision of the subject matter.
However, as a general rule, an individual 3GPP TS or 3GPP TR shall be prepared for each subject to be standardized, and published as a complete entity. In specific cases and for practical reasons, for example:
  • the 3GPP TS or 3GPP TR is likely to become too voluminous;
  • subsequent portions of the content are interlinked;
  • portions of the 3GPP TS or 3GPP TR could be referred to in regulations; or
  • portions of the 3GPP TS or 3GPP TR are intended to serve for certification purposes,
the 3GPP TS or 3GPP TR may be split into separate parts under the same number. This has the advantage that each part can be changed separately when the need arises.
In particular, the aspects of a product which will be of separate interest to different parties (e.g. manufacturers, operators, certification bodies, legislative bodies) shall be clearly distinguished, preferably as parts of a 3GPP TS or 3GPP TR or as separate 3GPP TSs or 3GPP TRs.
Such individual aspects are, for example:
  • performance requirements;
  • maintenance and service requirements; and
  • quality assessment.
The terms that shall be used to designate the divisions and subdivisions that a 3GPP TS or 3GPP TR may have are shown in Table 1.
Term Example of numbering
part3GPP TS 21.299-1

5.1.2  Subdivision of the subject matter within a series of partsWord‑p. 11
There are two systems in use for subdividing into parts:
  1. Each part deals with a specific aspect of the subject and can stand alone.
  2. There are both common and specific aspects to the subject. The common aspects shall be given in part 1. Specific aspects (which may modify or supplement the common aspects and therefore cannot stand alone) shall be given in individual parts.
Where the system described in b) is used, care shall be taken that the references from one part to another are always to the latest version. There are two ways to achieve this:
  • If reference is made to a particular element, the reference shall be specific (see clause
  • Since the complete series of parts is normally under the control of the same TSG, the use of non-specific references (see clause is permitted, provided that corresponding changes are implemented simultaneously in all parts.
The use of non-specific references requires a high degree of discipline by the TSG responsible for the 3GPP TS or 3GPP TR.
Their use is not permitted between 3GPP TSs or 3GPP TRs of different Technical Bodies except where the reference is intentionally non-specific, i.e. it is accepted that it will be possible to use all future changes of the text referred to for the purposes of the referring 3GPP TS or 3GPP TR.
Each part of a multi-part 3GPP TS or 3GPP TR shall be drafted in accordance with the rules for an individual 3GPP TS or 3GPP TR as specified in the present document.

5.1.3  Subdivision of the subject matter within an individual 3GPP TS or 3GPP TRWord‑p. 12
Type of element Arrangement of elements in 3GPP TS or 3GPP TR (note 1) Permitted content of element(s) in 3GPP TS or 3GPP TR (note 1)
Informative preliminaryTitle pagestitle, number, logo(s), copyright statement, etc
Table of contents(generated content, see clause 6.1.2)
Forewordtext (note 3)
Introductiontext, figures, tables, notes
Scopetext, figures, tables, notes
Referencesstock text followed by numbered references of documents specifically cited in the TS/TR (note 4)
Definition of terms, symbols and abbreviationsstock text plus specific definitions (note 4) text, notes
Normative technical (TS)
Informative technical (TR)
Clauses comprising the main body of the documenttext, figures, tables, notes, equations (note 2)
Normative supplementary (TS)Annexestext, figures, tables, notes, equations (notes 2, 5)
Informative supplementaryAnnexestext, figures, tables, notes, equations (notes 2, 5)
Bibliographyunnumbered list of documents for further reading not specifically cited elsewhere in the TS/TR
Change history annextable (notes 3, 6)
For an example of numbering of divisions and subdivisions see Annex B.
A 3GPP TS or 3GPP TR may also contain notes to figures and tables (see clauses  and

5.2  Description and numbering of divisions and subdivisionsWord‑p. 13

5.2.1  Parts and sub-parts

The number of a part shall be indicated by arabic numerals, beginning with 1, following the 3GPP TS or 3GPP TR number and preceded by a hyphen, for example:
  • 3GPP TR 21.999-1, 3GPP TR 21.999-2.

5.2.1A  General numbering issues

Every attempt shall be made to use continuous numbering as described in the remainder of 5.2. However, if continuous numbering cannot be maintained, a new element may be inserted in existing text using an appropriate alphanumeric designation that does not disturb the existing numbering scheme. This applies to all elements (e.g. clause, annex, figure, table, note, list).
It is necessary to update a 3GPP TS. A new clause needs to be inserted between the existing clauses 8 and 9. A new clause 8A may be inserted in preference to re-numbering the existing clauses.
A new figure needs to be inserted between existing figures 4 and 5. A new figure 4A may be inserted to avoid re-numbering of all subsequent figures.
Similarly, an existing element may be deleted and replaced with the term "Void." to minimize disruption to the numbering scheme. However, the title of the deleted element may be retained. See clause 5.2.1B for further details.
During the updating of a 3GPP TS, it is decided that annex C is no longer required. The title of annex C remains while the content simply becomes "Void.". Later annexes may therefore remain unchanged.
It is decided to delete a note 3, so the text of note 3 becomes "Void." and there is no need to re-number note 4.
Once a TS or TR is under change control, changing existing clause, figure, table, annex, etc. numbers is strongly deprecated, since external documents might reference specific clauses (figures, tables, ...) of the TS/TR.

5.2.1B  Removal of redundant numbered elements

As described in clause 5.2.1A, it is occasionally necessary to remove text which has become obsolete or redundant. If an entire clause, or figure, table, or other numbered element having a title is concerned, the preferred method is to eliminate the text of the clause and to replace the title with the word "Void" in round brackets. Alternatively, if it is felt important to leave some trace of the clause's subject material prior to its removal, the author of the Change Request could leave the title of the element unchanged, and delete just the body of the text of the clause (or figure, or table, …), replacing the text with the word "Void" in round brackets.
The following clause is to be removed:
11.2  Functional procedures associated with lunch
If a DISSOCIATE message is received containing the indicator "User out to lunch", then the equipment shall start timer T100 and respond with an ACKNOWLEDGE message containing the indicator "Have a nice siesta"
The preferred method, replacing the title of the clause with "Void" and deleting completely the text of the clause, yields:
11.2  (Void)
The alternative is to retain the title, and delete only the body text:
11.2  Functional procedures associated with lunch
Whichever method is used, the author of a Change Request provoking such a change shall ensure that any reference to the clause in question from elsewhere in the same TS or TR is eliminated by appropriate inclusion in the same Change Request. Ideally, the author should also check for references to that specific clause in other 3GPP TSs or TRs if he suspects there might be any, and raise appropriate Change Requests to those TSs or TRs to modify or eliminate those references.

5.2.1C  Avoidance of re-use of a voided element for a new purposeWord‑p. 14
A clause which has been voided using the procedures of clause 5.2.1B above shall not be re-used for a different purpose if at some subsequent moment it is necessary to add another clause in the same logical position as the clause previously voided.
That is, based on the example in clause 5.2.1B, a subsequent Change Request to add a clause entitled "Colour options for the on/off switch" - which patently has no relationship to the original clause 11.2 - shall not re-use clause 11.2, but shall be added as a clause with a completely new number (e.g. 11.3 or 11.2A).
The only circumstances in which re-use of a voided clause number might be appropriate is if the new clause were to have exactly or very nearly the same title as the original clause (in this case, "Functional procedures associate with lunch".
The same considerations apply to other numbered elements such as figures and tables.

5.2.2  Clause

The clauses in each 3GPP TS or 3GPP TR or part shall be numbered with arabic numerals, beginning with 1 for the "Scope" clause. The numbering should be continuous, see also clause 5.2.1A.
Each clause shall have a title (for formatting see clause 5.2.3).

5.2.3  Subclause

A subclause is a numbered subdivision of a clause. A primary subclause (e.g. subclause 5.1, 5.2, etc.) may be subdivided into secondary subclauses (e.g. subclauses 5.1.1, 5.1.2, etc.) and this process of subdivision may be continued as far as the sixth heading level (e.g. subclause
It is unnecessary to use the term "subclause" unless using the term "clause" would be ambiguous, for example, if in the context, it were not clear if the term "clause" referred only to the top level clause ("4") or to all the subclauses ("4.1", "4.1.1", "4.1.2", "4.2" etc) beneath the clause. Such ambiguity can only occur where there are hanging paragraphs; these are sometimes encountered in older 3GPP Technical Specifications and Technical Reports produced before the outlawing of hanging paragraphs (see clause 5.2.4).
Subclauses shall be numbered with arabic numerals, see also clause 5.2.1A.
A subclause should not be created unless there is at least one further subclause at the same level. For example, a piece of text in clause 10 should not be designated subclause "10.1" unless there is also a subclause "10.2".
Each subclause shall be given a title, which shall be placed after its number.
(Sub)clause titles shall be treated as normal text i.e. no additional capitalization; there should be no full stop at the end of a (sub)clause title.
  • Use the Heading style appropriate to its level.
  • Separate the number of the heading and the text of the heading with a tab.
  • Do not use automatic heading numbering; you may, however, use it as an initial aid when outlining the structure of your document, as long as it is eliminated before handover to the 3GPP Support Team.

5.2.4  ParagraphWord‑p. 15
"Hanging paragraphs" such as those shown in the following example shall be avoided since reference to them is ambiguous.
In the following example, the hanging paragraphs indicated cannot be uniquely identified as being in "clause 5" since strictly speaking the paragraphs in 5.1 and 5.2 are also in clause 5. To avoid this problem it would be necessary either to identify the unnumbered paragraphs as clause "5.1 Xxxxxxxxxxxx" and to renumber the existing 5.1 and 5.2 accordingly (as shown), or to add a new clause header immediately below the header for clause 5 numbered it 5.0.
If hanging paragraphs are to be removed from a TS or TR already under change control, the renumbering of existing clauses being deprecated (see clause 5.2.1A), the newly introduced clause shall be numbered 5.0 (using the above example) and clauses 5.1 and 5.2 remain unchanged.
Permitted Not permitted
  5  Designation
  5.1  Xxxxxxxxxxx
  xxx x  xxxx  xxxx
  xxx x  xxxx  xxxx
  5.2  Xxxxxxxxxxx
  xxx x  xxxx  xxxx
  5.3  Xxxxxxxxxxx
  xxx x  xxxx  xxxx
  xxxx xxxx
  6  Test report
  5  Designation
  xxxx x   xxxxxxx  }
  xxxx x   xxxxxxx  }  hanging paragraphs
  xxxx x   xxxxxxx  }
  5.1  Xxxxxxxxxxx
  xxx x  xxxx  xxxx
  5.2  Xxxxxxxxxxx
  xxx x  xxxx  xxxx
  xxxx xxxx
  6  Test report

5.2.5  Lists

Lists may be introduced by a sentence, a complete grammatical proposition followed by a colon, or by the first part of a proposition (without a colon), completed by the items in the list.
Each item in a list shall be preceded by a dash.
   - list item 1;
   - list item 2.
If necessary for identification, a lower-case letter followed by a parenthesis may be used. If it is necessary to subdivide an item further in this type of list, arabic numerals followed by a parenthesis shall be used (see also clause 5.2.1A).
   a) list item a;
   b) list item b;
      1) list item a1;
      2) list item a2.
Respect normal rules of punctuation: if the elements of a list are cast as phrases of a sentence which introduces the list, start each element with a lower case letter and end it with a semicolon. End the last item in the list with a full stop, unless the introductory sentence continues after the end of the list, in which case use the most appropriate punctuation (semicolon, comma, or none). If, however, each element of a list is a self-contained sentence, begin each with a capital letter and end each with a full-stop.
Use "and" or "or" at the end (following the semicolon) of the penultimate element of a list to indicate unambiguously whether the elements are combinable or whether they are mutually exclusive.
  • Use the appropriate bullet styles, i.e. styles B1 to B5.
  • Separate the list item identifier (e.g. bullet) and the text with a tab (if not using automatic bullets and numbering).
  • Ensure that the formatting of the lists is consistent throughout the deliverable.

5.2.6  AnnexWord‑p. 16
Each annex shall start on a new page.
For the description of normative and informative annexes, see clauses 6.3.8 and 6.4.1.
Each annex shall be designated by a heading comprising the word "Annex" followed by a capital letter designating its serial order, beginning with "A", e.g. "Annex A" (see also clause 5.2.1A). The annex heading of a TS shall be followed by the indication "(normative):" or "(informative):", and by the title on the next line. In the case of a TR, the entire document is informative, so the text "(normative):" or "(informative):" shall be omitted.
   Annex A (normative):
   Title of annex A
Numbers given to the clauses, clauses, tables, figures and mathematical formulae of an annex shall be preceded by the letter designating that annex followed by a full-stop (e.g. figure B.1, table C.4). The numbering shall start afresh with each annex. A single annex shall be designated "Annex A".
Clauses in annex A shall be designated "A.1", "A.2", "A.3", etc. (see also clause 5.2.1A).
For endorsement of documents from other standards organizations, see annex J.
  • Insert a manual page break before the title line of each annex. Use the Heading 8 style (for 3GPP TSs) or Heading 9 style(for 3GPP TRs) for the annex heading. Insert a line break (↵ "shift" + "enter") between the colon and the title.
  • For all clause headings use the appropriate Heading styles, starting from Heading 1, e.g. for clause A.1 use Heading 1, for A.1.1 use Heading 2. Do not insert manual page breaks before each clause of an annex.

5.2.7  Bibliography

A bibliography, if present, shall appear after the penultimate annex entitled "Bibliography".

5.2.8  Index

An index, if present, shall appear as the last element. The title shall be "Index".
  • Use Heading 1 style for the title.

5.2.9  Change history

Shall appear as the last element (informative annex).
  • Use Heading 1 style for the title.

5.3  Consistency amongst ReleasesWord‑p. 17
In line with the general provisions of clause 4.2 (homogeneity), it is essential to preserve insofar as possible the structure of a TS or TR from one Release to another.
This is particularly important when voiding clauses (or figures, notes, etc) and when adding new clauses (figures, notes, etc). If a new clause is introduced, it shall be added in the logically correct place and shall be given a new clause number. It is not acceptable to re-use an existing, redundant, clause (ie one which had previously been used but has subsequently been voided).
Similarly, if an identical or near identical provision is introduced into two or more Releases, the provision should use the same clause (or figure, note, etc) number in each Release instance of the TS or TR. This may mean introducing void padding clauses (or figures, notes, etc) in older Release instances in order to keep the numbering aligned.
The structure of the Release 10 version of a TS is
   5.3  Some provision
   5.4  Another provision
   5.5  A third provision
and, due to extra functionality having been added in the Release 11 instance, the structure of the Release 11 version of the TS has become
   5.3  Some provision
   5.4  Another provision
   5.5  A third provision
   5.6  A new provision for Rel-11 only
   5.7  Another new Rel-11 requirement
   5.8  Something else peculiar to Rel-11
It is now decided to retrospectively add some requirement at Release 10, which will be mirrored in Release 11. The new clause shall have the same number in both Releases, with void padding clauses introduced into the Release 10 instance as necessary. Thus the structure of the Release 10 TS becomes
   5.3  Some provision
   5.4  Another provision
   5.5  A third provision
   5.6  Void
   5.7  Void
   5.8  Void
   5.9  An afterthought
and that of the Release 11 TS becomes
   5.3  Some provision
   5.4  Another provision
   5.5  A third provision
   5.6  A new provision for Rel-11 only
   5.7  Another new Rel-11 requirement
   5.8  Something else peculiar to Rel-11
   5.9  An afterthought
That is, the new provision takes the clause number 5.9 in each both Releases.

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