"how to use SHALL or MUST"

How it is interpreted or understanding the mean of
SHALL or MUST in specification.

Which one is a mandatory and which is optional.

Pardal

Both, in my opinion, are mandatory.  

'May' means that it is optional.

I believe SHALL is prefered over MUST, but both are a condition of a manditory requirement.  If you are trying to specify "optional" requirements you are heading down a painful path.  Specifications have to be black & white, clear-cut, etc, etc.

Wanna Tip? FAQ731-376
"Probable impossibilities are to be preferred to improbable possibilities."

Shall in codes denote a mandatory requirement.

Should denotes a recommended practice, but not required.

May denotes an option.

Must is not used too much anymore in code lexicon.
(No pun on the last one intended)

Thanks all you .

Pardal

I agree in general with the comments above.

To be strict, each code "should" in general define these words on the "Scope and Definitions" section.

Mentioning these definitons may be helpful to sustain your interpretations of a code.

For example ASME/ANSI codes, defines their version for should, shall, may. NFPA defines should, shall, etc.

Hi David:

Thanks for your tip.

Could be any way you can send me such pharagraph from that code??

Pardal

You might also wish to peruse MIL-STD-961D, which can be downloaded from

http://assist2.daps.dla.mil/quicksearch/

961D is the specification for specifications and paragraph 4.9.6 Commonly used words and phrases  describes in detail the recommending wording for specification paragraphs.

TTFN

Ok...

NFPA 13.
Should. Indicates a recomendation or that which is advised but not required.

(The manual of this code clarifies that it refers to appendix A or B contents).

Shall. Indicates a mandatory requirement.

ASME B31.1. 100.2
May: may is used to to denote permission, neither a requirement nor a recomendation.

Should: "should" or "it is recomended" is used to indicate that a provision is not mandatory but recomended as good practice.

(I have used the last phrase of this parragraph to sustain that even something that is not an obligation is correct and acording to a good ethics, a must).

Shall: Shall or shall not is used to indicate that a provission or prohibition is mandatory.

This is how the Norwegian offshore industry ( Norsok) define it:

Shall  Verbal form used to indicate requirements strictly to be followed in order to conform to the standard and from which no deviation is permitted, unless accepted by all involved parties.  

Should  Verbal form used to indicate that among several possibilities one is recommended as particularly suitable, without mentioning or excluding others, or that a certain course of action is preferred but not necessarily required.  

May  Verbal form used to indicate a course of action permissible within the limits of the standard.
Can  Verbal form used for statements of possibility and capability, whether material, physical or casual.

http://www.standard.no/standard/NORSOK_standards/L-001/general/L001-05.htm#P115_4100

Try to word your notes in the following format:

1)Command/Action (Drill, Clean, Mark, Install...)
2)Object
Examples:
Correct - 'MARK P/N AND REV LETTER WHERE SHOWN'
Incorrect - 'PART SHALL BE MARKED WITH REV LETTER...'

Correct - 'USE MINIMUM BEND RADII'
Incorrect - 'ALL BENDS SHALL BE MINIMUM BEND RADII'

This eliminates the 'shall, should, must, will' controversy entirely. In addition, it's best to try to put your notes in the sequence in which they are performed - start with material and end with marking or packaging.

An exception to item 1 above is that "DRILL" should not be used on a drawing.  The purpose of a drawing is to define the part, not the method (unless the method is critical to part functionality).  The same may be said for "THREAD" or "TAP" (size callout should be sufficient).  If these commands were required, wouldn't "MACHINE" and "MILL" also be reqired?  It makes no difference how the machinist achieves a feature, as long as the feature meets the drawing requirements.

Hi EWH , beside you are rigth  regarding to drawings, my question was related to writed specification such as the specification on a bid requested.

Pardal

Hi Pardal,
  I apologize for going off on a tangent.  One of my pet peeves is seeing excess verbage on drawings.  It is a different matter regarding processes and specifications.

As I have stated in my response, you are better off just telling whomever is making the part(s) to just do what you need done instead of using MUST or SHOULD or MAY. Reword your notes to say: "DO THIS" not "THIS SHOULD BE DONE"
Then your question becomes mute.

It hard to find a bid specification with the "DO THIS"
I allways saw "shall be done"  or "must be done"
That's what  I want to know.

"The way I shall consider  the phrase "
or "I Must consider the phrase"

Thanks

Pardal

I know it sounds aggressive but when you are giving someone directions, you don't say "A right turn shall be taken" - you just say "Turn right" It really is the same on a drawing. I have debated this with many QC guys and they always agree once they see it in writing. You are not being impolite when you detail a drawing with instructions. Also, there are even times when the vendor wonders "Who shall do this - me or the customer?" But when you say:
NOTES:
1. WELD PER AMS D1.1
2. ORIENT THREADED END OF COUPLING TO OUTSIDE OF TANK
3. MASK THREADS BEFORE PAINTING
4. MARK PART NUMBER WHERE SHOWN

No one will wonder what you want or who is responsible for doing it. Trust me it works better this way. Also, try to put notes in order of operation. I won't answer again but I wanted you to get a full understanding of my intent in this answer.
Thanks for listening.
Kim

Kim, I'm a qualitygeek & you'll get no argument from me. I'm a firm believer in the KISS rule for documentation (including drawings, procedures, policies,...et al & so forth...)

I agree with Kim,
The notes should (not shall..hee hee) be to the point and not drawn out.
It helps to have them in order of operation sa Kim writes.

     At the risk of adding more confusion to this topic I'll submit this:

     All Technical English and Technical Writing manuals/textbooks, not to mention English grammar textbooks, I have read advise against using "shall" in any way shape or form.  The manuals cite something similar to KimBellingrath's suggestion: "Omit will, shall, must, etc".

     (The most famous misuse of "shall" was Gen Mcarthur saying "I shall return".  Aparantly he should have said "I will return".  Though the latter doesn't have the same "kick" it is more grammaticaly correct.)

procadman2
Proe Design & Admin
NASA Contractor

"You can't build a reputation on something you haven't done."
H Ford

No confusion.

No one here would argue that a requirements specfication is remotely an example of normal English literature.

TTFN

KimBellingrath recommends using the active voice instead of the passive voice.  Write the specification using commands.
Consider, Provide, Furnish, Install, Clean, Submit, Weld, Ship, Design, Calculate, ...  Combine to clarify the scope.  Furnish and install.  Avoid "by others" if you can identify the others.  As Kim said, "Do it" instead of "it shall be done".

After writing the specification search for any use of passive words such as shall, must, have, ...  At first, use the grammer check software with passive voice rule turned on to help you get the style.

For practice, edit examples of government regulations that are almost exclusively passive voice.  With practice you can enjoy this newly found language.

John

Kim's examples are work instructions, which are appropriate for assembly and fab drawings, since it's a communication between the engineer and the fabricator.

A "specification" is a set of requirements that are to be adhered to by the design, so it's somewhat odd to say, "Communicate to the outside world using TCP/IP." as there is no one on the other side of this imperative execute this command.  

Specification drawings detail inherent properties of the item, such as performance, weight, etc.  You don't tell your laptop, "Weigh no more than 10 pounds."  However, "Laptop shall weigh no more than 10 pounds," makes sense as a requirement.

Moreover, defense specification drawings must adhere to MIL-STD-961, which mandates the use of "shall" to express a binding requirement.

TTFN

We issue specifications for equipment, services, etc.  Let’s say that this is a specification submitted to various suppliers to bid on your laptop computer.  It is perfectly acceptable to specify a communication interface such as “Furnish the computer with at least two 100baseT Ethernet communications ports for an interface to widgets using TCP/IP."  This is a clear requirement.  If the computer has three Ethernet ports it is OK provided that at least two are 100baseT.  Further, perhaps you have to carry the computer up three flights of stairs each morning.  You could passively write “The weight of the computers shall not exceed 5 kg (11 pound).”  Furnish computers weighing 5 kg (11 pound) or less.  Each make sense as a requirement.  If the computers proposed weigh 6 kg they are not fully compliant with the specification.

John

What you are describing is a statement of work, not a design specification.  "Furnish" is an imperative that requires an action, hence is a statement of work to be accomplished.  It implies that the subject can design OR procure to meet the requirement.  This is typical of procurement contracts not specifications.

MIL-STD-961 covers specifically what are called Prime Item Development Specifications, which are DESIGN requirements, otherwise, a totally different agency would be responsible for procurement.  While sloppy language allows for "Design computer to weigh less than 10 pounds,"  when you have >300 such requirements all starting with "Design computer" it becomes pointless to have an active voice.

TTFN

MIL-STD-961 is another example of Military versus the real technical world.  

I have a manual written by someone who assumes he understands 961.

Instead of listing required steps in a standard fashion, ie: 2.1 2.1a 2.2 etc., the author begins each requirement with "shall".  This goes on for over 20 steps. This is not what 961 is stating to do.

Using "shall" and "must" in most cases draws the readers attention away from the rest of the requirements.  All of the requirements must be met.  Some are more critical than others.

"The weight of the computers to not exceed 5 kg." is acceptable technical english.

However it is still needlessly wordy.  It would be better to put all over-all requirements in a list and give a range of acceptable values:

weight: 4-5kg

or weight: <5kg

"Shall" and "must are leftovers from the dark ages.

I will not use them, even under 961, when I can have a more easily read technically correct rewriten requirement.


(FYI.  All of my work goes to NASA.)

procadman2
Proe Design & Admin
NASA Contractor

"You can't build a reputation on something you haven't done."
H Ford

procadman2
Well said. I agree and also follow your same guidelines.
I think 'shall' and some other sayings were brought into our language by the movie/tv industry ~30-40 years ago!