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Content for  TR 21.801  Word version:  16.2.0

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6.6  Common rules and elements

6.6.1  Verbal forms for the expression of provisions

A 3GPP TS does not in itself impose any obligation upon anyone to follow it. However, such an obligation may be imposed, for example, by legislation or by a contract. In order to be able to claim compliance with a 3GPP TS, the user needs to be able to identify the requirements that are obligatory. The user also needs to be able to distinguish these requirements from other provisions where there is a certain freedom of choice.
Clear rules for the use of verbal forms (including modal auxiliaries) are therefore essential. Annex E gives, in the first column of each table, the verbal form that shall be used to express each kind of provision. The equivalent expressions given in the second column shall be used only in exceptional cases when the form given in the first column cannot be used for linguistic reasons.
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6.6.2  Spelling and abbreviation of names of organizations, and style

The spelling of the names of organizations, and their abbreviations, shall be as used by those organizations.
To facilitate understanding by all readers, the style shall be as simple and concise as possible. This is particularly important for those readers whose first language is not English.
The "Shorter Oxford English Dictionary" and the "Concise Oxford Dictionary" are suggested.
Abbreviations shall be used with care, and their use shall be limited to those cases where it is not likely to cause confusion.
An abbreviation shall be defined only if used subsequently in the 3GPP TS or 3GPP TR.
The general rule is that abbreviations consisting of the initial letters of words be printed in lower-case letters (for example, "a.c." for "alternating current") and a full-stop be placed after each letter. Where, however, an abbreviation comprises capital letters, no full-stops are required.
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6.6.2A  Use of capital lettersWord‑p. 25
Unnecessary use of capital letters should be avoided.
EXAMPLE:
"user" is preferred to "User".

6.6.2B  Pagination

Unnecessary pagination, (i.e. use of hard page breaks) should be avoided.
  • Use Format | Paragraph | Text Flow | Keep Lines Together and Keep with Next attributes instead of "hard" page breaks.

6.6.3  Use of trade names

A correct designation or description of a product shall be given rather than a trade name (brand name).
Proprietary trade names (i.e. trade marks) for a particular product should as far as possible be avoided, even if they are in common use.
If, exceptionally, trade names cannot be avoided, their nature shall be indicated, e.g. by the symbol ® for a registered trade mark (see example 1).
EXAMPLE 1:
Instead of "Teflon®", write "polytetrafluoroethylene (PTFE)".
If it is known that only one product is currently available that is suitable for the successful application of the standard, the trade name of the product may be given in the text of the standard but shall be associated with a note as shown in example 2.
EXAMPLE 2:
If it is considered to be essential to give an example (or examples) of commercially available products suitable for successful application of the standard because the product characteristics are difficult to describe in detail, trade names may be given in a note as shown in example 3.
EXAMPLE 3:
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6.6.4  Figures

6.6.4.1  Usage

Figures should be used wherever appropriate to present information in an easily comprehensible form.

6.6.4.2  Format

  • Use the TH style on the paragraph which contains the figure itself.
  • Maximum size for figures is 17 cm by 22 cm.
Where SDL, Program Code, ICS, or TTCN is included in figures it shall be prepared in accordance with Annex I.

6.6.4.3  NumberingWord‑p. 26
Figures may be numbered sequentially throughout the document without regard to the clause numbering, e.g. first figure is figure 1 and the twentieth figure (in, say clause 7) is figure 20.
Figures may also be numbered taking account of clause numbering.
EXAMPLE 1:
First figure in clause 7 is figure 7.1, fifth figure in clause 7 is figure 7.5.
EXAMPLE 2:
First figure in clause 7.3.2 is figure 7.3.2.1, fifth figure in clause 7.3.2 is figure 7.3.2.5.
One level of subdivision only is permitted (e.g. figure 1 may be subdivided as 1 a), 1 b), 1 c), etc.). See also clause 5.2.1A. For the numbering of figures in annexes, see clause 5.2.6.
  • You may use sequence fields for automatically numbering figures. See clause H.4: "Sequence numbering".
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6.6.4.4  Layout of title

The figure title shall be below the figure. An explicit figure name is optional. See the following examples:
EXAMPLE 1:
Figure 1: Details of apparatus
EXAMPLE 2:
Figure 1
  • Use the TF style.
  • If applicable, the figure number is followed by a colon, a space and the figure name

6.6.4.5  Choice of letter symbols, style of lettering, and labelling

  • Use Arial font.
  • Use a font size of at least 8 points (final size), to ensure legibility.

6.6.4.6  Technical drawings

Void.

6.6.4.7  Diagrams

Void.

6.6.4.8  Notes to figures

Notes to figures shall be treated independently from notes integrated in the text (see clause 6.5.1). They shall be located above the title of the relevant figure. A single note in a figure shall be preceded by "NOTE:". When several notes occur in the same figure, they shall be designated "NOTE 1:", "NOTE 2:", "NOTE 3:", etc. (see also clause 5.2.1A). A separate numbering sequence shall be used for each figure.
Notes to figures may contain requirements.
  • Write notes to a figure using the word processor rather than embedding them in the figure itself.
  • Use the NF style.
  • Separate NOTE: from the text of the note with a tab.
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6.6.4.9  Footnotes to figuresWord‑p. 27
Footnotes shall not be used in 3GPP TSs or 3GPP TRs.

6.6.5  Tables

6.6.5.1  Usage

Tables should be used wherever appropriate to present information in an easily comprehensible form.
A table within a table is not permitted. Subdivision of a table into subsidiary tables is not permitted.
  • Centre tables horizontally.
  • The "space between columns" is 0,1 cm.
  • Maximum width for tables in portrait orientation: 17 cm and for landscape orientation: 22 cm.
  • Set table columns widths in centimetres (not inches).
  • Use borders to separate the rows and columns of tables, as appropriate; the precise format will depend on the structure of each table, but be consistent throughout a deliverable (or series of related deliverables). Borders should be &frag34; pt single line.
  • Each table shall be followed by an empty "Normal" style paragraph ("Enter" key).
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6.6.5.2  Numbering

Tables may be numbered sequentially throughout the document without regard to the clause numbering, e.g. first table is table 1 and the twentieth table (in, say clause 7) is table 20.
Tables may also be numbered taking account of clause numbering.
EXAMPLE 1:
First table in clause 7 is table 7.1, fifth table in clause 7 is table 7.5.
EXAMPLE 2:
First table in clause 7.3.2 is table 7.3.2.1, fifth table in clause 7.3.2 is table 7.3.2.5.
See also clause 5.2.1A. For the numbering of tables in annexes, see clause 5.2.6.
  • You may use sequence fields for automatically numbering tables. See clause H.4: "Sequence numbering".
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6.6.5.3  Layout of title

The title shall be above the table. An explicit table name is optional. See the following examples:
EXAMPLE 1:
Table 1: Electrical properties
EXAMPLE 2:
Table 1
  • Use the TH style.
  • If applicable, the table number is followed by a colon, a space and the table name

6.6.5.4  Headings

The first word in the heading of each column shall begin with a capital letter. The units used in a given column shall generally be indicated under the column heading.
EXAMPLE:
Type Linear density (kg/m) Inside diameter (mm) Outside diameter (mm)
       
  • Use of the table headings tool (Table, Heading row repeat) is encouraged for tables that require more than one page.
  • Use the following styles:
       Table Headings           TAH
       Text Left justified      TAL
       Text Centred             TAC
       Text Right justified     TAR
    
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6.6.5.5  Continuation of tablesWord‑p. 28
The column headings shall be repeated on all pages after the first (see clause 6.6.5.4).

6.6.5.6  Notes to tables

Notes to tables shall be treated independently from notes integrated in the text (see clause 6.5.1). They shall be located within the frame of the relevant table. A single note in a table shall be preceded by "NOTE:". When several notes occur in the same table, they shall be designated "NOTE 1:", "NOTE 2:", "NOTE 3:", etc. (see also clause 5.2.1A). A separate numbering sequence shall be used for each table.
Notes to tables may contain requirements.
  • Use the TAN style.
  • Include notes to a table within its borders in one cell, at the bottom.
  • Merge all cells to one, as in the following example:
EXAMPLE:
Column 1 cell Column 2 cell Column 3 cell Column 4 cell
NOTE: This cell is a merged cell.
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6.6.5.7  Footnotes to tables

Footnotes shall not be used in 3GPP TSs or 3GPP TRs.

6.6.6  References

6.6.6.1  General

As a general rule, references to particular pieces of text shall be used instead of repetition of the original source material, since such repetition involves the risk of error or inconsistency and increases the length of the document. However, if it is considered necessary to repeat such material, its source shall be identified precisely. If it is necessary to reproduce text from a work other than a 3GPP TS or TR, appropriate copyright permission shall be obtained.
References shall be made in the forms indicated in clauses 6.6.6.2 to 6.6.6.5 and shall not be made to page numbers.
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6.6.6.2  References to the 3GPP TS or 3GPP TR as a whole in its own textWord‑p. 29
The form "the present document …" shall be used.

6.6.6.3  References to elements of text

Use, for example, the following forms:
  • "in accordance with clause 3";
  • "according to clause 3.1";
  • "as specified in clause 3.1 b)";
  • "details as given in clause 3.1.1";
  • "see annex B";
  • "the requirements given in clause B.2";
  • "see the note in table 2";
  • "see example 2 in clause 6.6.3";
  • "see note 3 in clause 6.6.1".
It is required to use the terms clause and annex where applicable.
If there is a need to refer to an unnumbered list item in another standard, the following formulation shall be used:
"as specified in TS 21.299 [n] in clause 3.1, second list item".
Lower case letters are recommended (e.g. clause 1, annex A), however capital letters are also acceptable (e.g. Clause 1, Annex A). Usage should be consistent throughout the document.
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6.6.6.4  References to tables and figures

Every table and figure included in the 3GPP TS or 3GPP TR shall be referred to in the text.
Use, for example, the following forms:
  • "given in table 2";
  • "(see table B.2)";
  • "shown in figure A.6";
  • "(see figure 3)".
Lower case letters are recommended (e.g. table 1, figure 2), however capital letters are also acceptable (e.g. Table 1, Figure 2). Usage should be consistent throughout the document.

6.6.6.5  References to other documents

6.6.6.5.1  General
References to other documents may be specific or non-specific. All references, specific and non-specific, shall be given in the "References" clause (see clause 6.1.6).
6.6.6.5.2  Specific references
Except as provided for in clause 6.6.6.5.3, references shall be specific (identified by date of publication, edition number, version number, etc.).
In the body of the text, use the following form:
  • " … in accordance with TS 21.299 [n] … ".
For specific references, it is permissible to refer to a specific clause, figure or table of the referenced document. However, great care needs to be taken, especially when referencing documents still under development, and such referencing of specific clauses, figures or tables is to be avoided if there is a reasonable chance that the structure of the referenced document may change in time.
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6.6.6.5.3  Non-specific referencesWord‑p. 30
Non-specific references may be made only if it is accepted that it will be possible to use future changes of the document referred to for the purposes of the referring 3GPP TS or 3GPP TR.
In the case of references to 3GPP TSs and TRs, unless otherwise indicated, a non-specific reference refers to the TS or TR in the same Release as that of the referring TS or TR. It is implicitly to the latest version of the referenced TS or TR in the Release in question.
For non-specific references, it is not permissible to cite particular clauses, figures or tables, since it cannot be guaranteed that the numbering will be unchanged in later versions of the referenced document.
In the body of the text, use the forms as given in clause 6.6.6.5.2.
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6.6.6.6  Numbering

References in clause 2 shall be numbered sequentially. If a reference is removed when a specification is under change control, the entry in clause 2 shall be replaced by a [void] entry, using the same principle as for deletion of clauses.
  • You may use sequence fields for automatically numbering references. See clause H.4: "Sequence numbering".
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6.6.7  Representation of numbers and numerical values

For decimal and thousands separator characters, one of the following options shall be employed:
  • Option 1: The decimal sign shall be a comma. The thousands separator shall be a space.
  • Option 2: The decimal sign shall be a full-stop (period). The thousands separator shall be a comma.
The chosen option shall be used throughout the TS or TR. It is not permissible to mix the two systems in a single document. If there is any ambiguity as to which system is in use, the characters in question shall be defined as symbols in clause 3.3 of the TS or TR. For example, unless there are other instances nearby in the document, the string 234,557 is ambiguous (is it two hundred and thirty four point five five seven or two hundred and thirty four thousand five hundred and fifty seven?). The present document uses Option 1.
If a value less than 1 is written in decimal form, the decimal sign shall be preceded by a zero.
EXAMPLE 1:
0,001 (not ,001)
Each group of three digits reading to the left or to the right of a decimal sign shall be separated by a space from preceding digits or following digits respectively, except for four-digit numbers designating years.
EXAMPLE 2:
23°456 / 2°345 / 2,345 / 2,345°6 / 2,345°67 but the year 1997
For clarity, the symbol × or a lower case x (rather than a point or any other symbol) shall be used to indicate multiplication of numbers and numerical values.
EXAMPLE 3:
write 1,8°×°10-3 (not 1,8 * 10-3 or 1,8 ⋅ 10-3 or 1,8 . 10-3)
To express numbers of items (as opposed to numerical values of physical quantities), the numerals one to nine shall be spelt out in full.
EXAMPLE 4:
"Carry out the test on five tubes, each 5 m long."
EXAMPLE 5:
"Select a further 15 tubes for the pressure test."
Preserve document identities as in the original titles.
EXAMPLE 6:
ISO/IEC°10531-1 (not ISO/IEC 10°531-1).
EXAMPLE 7:
3GPP°TR°21.801.
Put a non-breaking space between a number and its unit - including the percent sign (%) - even if the unit is not abbreviated:
EXAMPLE 8:
Write a number preceded by an unary operator (sign) without an intervening space:
EXAMPLE 9:
… a level of -3°dB …
Put a non-breaking space both before and after binary operators (+, -, x, etc.):
EXAMPLE 10:
a°+°b°=°c
  • Use non-breaking spaces (Ctrl + Shift + space) for the thousand separator, before and after binary operators and preceding units.
  • Use a non-breaking hyphen (Ctrl + Shift + -) for the minus sign.
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6.6.8  Quantities, units, symbols and signsWord‑p. 31
The units in which any values are expressed shall be indicated.

6.6.9  Mathematical formulae

6.6.9.1  Types of equations

Equations between quantities are preferred to equations between numerical values. Equations shall be expressed in mathematically correct form, the variables being represented by letter symbols the meanings of which are explained in connection with the equations, unless they appear in a "Symbols and abbreviations" clause (see clause 6.3.2). Descriptive terms, acronyms or names of quantities shall not be arranged in the form of an equation.
EXAMPLE:
3GPP drafting: formula example
where:
  • xj are samples of time errors data;
  • N is the total number of samples;
  • τ is the time error sampling interval;
  • n is the number of sampling intervals, with n = 1,2,...,integer part (N/3).
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6.6.9.2  Presentation

Use the EQ style.
Insert one tab before the equation to center it.
The equation editor sizes and styles should be respected as shown in the following examples:
3GPP drafting: equation editor sizes and styles

6.6.9.3  NumberingWord‑p. 32
If it is necessary to number some or all of the formulae in a 3GPP TS or 3GPP TR in order to facilitate cross-reference, arabic numbers in parentheses shall be used, beginning with 1:
   x2 + y2 < z2                     (1)
Equations may be numbered sequentially throughout the document without regard to the clause numbering, e.g. first equation is equation 1 and the twentieth equation (in, say clause 7) is equation 20.
Equations may also be numbered taking account of clause numbering.
EXAMPLE 1:
First equation in clause 7 is equation 7.1, fifth equation in clause 7 is equation 7.5.
EXAMPLE 2:
First equation in clause 7.3.2 is equation 7.3.2.1, fifth equation in clause 7.3.2 is equation 7.3.2.5.
See also clause 5.2.1A. For the numbering of equations in annexes see clause 5.2.6.
  • You may use sequence fields for automatically numbering tables. See clause H.4: "Sequence numbering".
  • Insert a tab between the equation and the number to right-align the number.
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6.6.10  Indication of dimensions and tolerances

Dimensions and tolerances shall be indicated in an unambiguous manner.
EXAMPLE 1:
80 mm°×°25 mm°×°50 mm (not 80 × 25 × 50 mm)
EXAMPLE 2:
80 μF°±°2 μF   or   (80 ± 2) μF
EXAMPLE 3:
16 kbit/s to 64 kbit/s (not 16 to 64 kbit/s)
EXAMPLE 4:
0 °C to 10 °C (not 0 to 10 °C)
In order to avoid misunderstanding, tolerances on percentages shall be expressed in a mathematically correct form.
EXAMPLE 5:
Write "from 63°% to 67°%" to express a range.
EXAMPLE 6:
Write "(65°±°2)°%" to express a centre value with tolerance.
The form "65°±°2°%" shall not be used.
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