Two Hour Parking

A street sign which says "2 hour parking  7am - 6pm  Except-Sun.-Hol.  Except By  Zone 4  Permit"

Signs such as this one are a common sight in Seattle's residential neighborhoods. I imagine the transportation department believes it to be clear and unambiguous. I beg to differ.

Your assignment for this week is to devise as many different interpretations of this sign as you can. Put your answers in the comments below or send them directly to me. I will post my answers (forty of them, plus another seventeen questions) next week, plus also explain what this exercise has to do with testing.

So what are you waiting for? Get busy!

*** Want a fun job on a great team? I need a tester! Interested? Let's talk: Michael dot J dot Hunter at microsoft dot com. Great testing and coding skills required.

Comments (15)

  1. David Drake says:

    Boy, that’s a tough one, since there are so many different combinations of those statements that are possible.

    Starting with the number "2":

    1. One may park here between 7AM and 6PM for 2 hours.

    2.  This is sign number 2 of a given series.  One may park here for an hour between 7AM and 6PM.

    3. This sign is incomplete.  There is a sign one, and it offers quite clear notes on parking, which ran over onto this sign, number two, which explains why the first statement is cut off at hour.

    Moving to the time span:

    1. One may only park in this area between 7AM and 6PM.  Parking outside that time span is forbidden.

    2. Parking is only restricted to the given time span between 7AM and 6PM.

    3.  One may park at 7AM or at 6PM for the given time span, but at no other times (the dash has an ambiguous meaning, as we’ll see when looking at Sun.-Hol)

    Moving to the first exception:

    1. Ignore all parking restrictions on SUN.-HOL.

    2. There is no parking at all on SUN.-HOL.

    3. On SUN.-HOL there is parking, but only for the given amount of time.

    4. If you park your car here on SUN.-HOL, you can leave it as long as want, locking you in for a permanent parking spot if your car breaks down.

    The meaning of SUN.-HOL:

    1. The exception (whatever it is) is applicable only on Sundays and Holidays.

    2. The exception is applicable when the weather sunny or during a nuclear holocaust.

    3. The exception is applicable for all days between Sundays and holidays (inclusive).

    4. The exception is applicable for all days between Sundays and holidays (exclusive).

    Finally, the last exception:

    1. Parking is not restricted in any way if you have a Zone 4 permit.

    2. Parking is not permissible ever if you have a zone 4 permit.

    3. The first exception is not applicable if you have a zone four permit.

    4. The first exception is always applicable if you have a zone four permit.

    5. This area is Zone 4 (whatever that means), except where permits are posted (Zone 4 is a different font; is it in the middle of the statement or does the exception wrap around it?)

    By assembling combinations of these 5 choices, I see 720 combinations, with many more possible.  Suddenly I feel much less worried about where I park; this would make for an interesting day in court.

  2. asymtote says:

    I doubt that the transportation department considers this sign to be absolutely clear and unambiguous but I think they probably do believe with good cause that it is sufficiently clear and unambiguous to the intended audience of people who are seeking to park in Seattle residential neighborhoods.

    Relevance to testing is that while a human will attempt to determine the intention of the author a computer will attempt to execute instructions according to set of very strict rules without regard to original intention. Any ambiguity in those instructions will cause undesired behavior. An objective of testing is to discover undesirable user experiences by seeking out areas of ambiguity.


  3. Bobbie the Programmer says:

    This is pretty clear.

    99% of people who drive would understand this to mean:

    2 hour parking between 7AM and 6PM.

    Parking is uncontrolled outside those hours or on Sundays and Holidays.

    This restriction does not apply to vehicles with Zone 4 permits.

    That’s pretty clean.

  4. Zach Fisher says:


    The "-" sign denoted a span of time in the context of "7AM-6PM"

    So I can read it to mean 7AM TO 6PM?

    Do I interpret the line below it to mean "EXCEPT TO SUN TO HOL"?

    What is "-SUN.-HOL"?

    Are they necesarily linked? Mutually exclusive?

    Is it a math equation?

    Is there such a thing as +SUN.+HOL?

    It appears that -SUN. is an abbreviation, but -HOL is not.

    Assuming -SUN = SUNDAY, what day of the week does -HOL map to?

    Assuming -HOL = HOLIDAY:

    What holidays are included?

    Are international holidays acceptable?

    Are state holidays in other states acceptable?

    Because holidays originate from "Holy Days", does this rule apply on the anniversary of the founding of my religious sect.


    The "2" color scheme is inverted.

    Is 2 a part of the statement? Can I exclude it? ( i.e., 2 HOUR PARKING or HOUR PARKING. )

    Is 2 used to denote that it is the second of a series of signs explaining parking rules?

    The "EXCEPT BY ZONE 4 PERMIT" appears in a different section. Does it pertain to the 2 hour parking rule or some other implied rule.

    Pedantic Parking

    So can we double park during this window of time?

    Can I park my boat? My bicycle?

    If my vehicle is not in "Park", am I parked?

    If my vehicle is still runnning, am I parked?

    How far do I have to move my vehicle before it is considered to be no longer parked in the same spot?

    Does this rule apply to government vehicles? meter maid vehicles? Cop cars? Fire Engines?

    Does the rule apply to all spaces before the sign? after the sign? both? Does it apply to this space only?


    If I parked at 6:59 AM, can I park until 8:58 AM? 8:59 AM? 9:00 AM?

    What about on Sundays?

    What about on Holidays?

    If I parked at 5:00 AM, do I have to move my car at 7:00 AM?

    What about on Sundays?

    What about on Holidays?

    If I parked at 5:59 PM, can I park until 7:58 PM? 7:59 PM? until 8:00 PM?

    What about on Holidays?

    If I parked at 4:00 PM, do I have to move the car at 6:00 PM?

    What about on Sundays?

    What about on Holidays?

    Does a ZONE 4 PERMIT allow me to bypass this rule? Or does it subject me to a more stringent set of rules?

    If I were to get a ZONE 4 PERMIT and set it next to my parked vehicle, can I park as long as I want whenever I want?

    Do I HAVE to park for 2 hours during this window?

    what is the exception on Sundays and Holidays?

    Can I NOT park? Can I park for MORE than 2 hours?

    The cop writing my ticket says 2 hours. I say 1 hour 59 minutes. Is the cop ALWAYS right?

    Crime & Punishment

    I park in such a way that is invalid to this sign.

    What consequences are there? A ticket? Towing? Fine? Jail? Death sentence? Nothing?

    My vehicle is one that transports cars to car dealerships. I am carrying 10 cars. Do I receive a punishment for each vehicle INCLUDING the transport vehicle?

  5. Jamie Akers says:

    And that Bobbie is why you work as a programmer and not a tester…

  6. @Bobbie the Programmer: but then again, that’s us programming guys not thinking beyond the obvious 🙂 We have to leave it to the test guys (see David’s comment) to see if what we make is as obvious as *we* think. I’m definitely not a tester but far too often I *thought* to understand what the customer meant, only to find out later that it was a complete misunderstanding…

  7. Kyralessa says:

    Reminds me of my favorite sign in Cincinnati:


    EXCEPT 4-6 pm Mon-Fri"

    The first time I saw that, I was baffled: "So where do they put the lane when it’s not 4-6pm Mon-Fri?"

    [What it actually means, of course, is that it’s OK to park in that lane…except during evening rush hour.]

  8. Hafthor says:

    Parking, the act, if it occurred before 7am is okay, right?

    Are Zone 4 permit holders forbidden from parking there even on holidays and Sundays?

    It appears as though I could park my car at 4pm and leave it until 9am the next day.

  9. Zach and David: Yay you for so many possibilities! Including a few I hadn’t thought of – most excellent!

  10. Zach Fisher says:

    Thought of one recently, but was unable to enter it in tonight:

    "Parking" could be imply that I cannot park the vehicle in some location for a particular amount of time during certain days of the year.

    "Parking" could imply that someone else can park my vehicle in some location for a particular amount of time during certain days of the year.

    Thanks for the mental exercise!

  11. Jeroen says:

    When I saw this post I thought about how to approach this. You can define all kinds of scenarios with certain values. Argue about the meaning of dashes and abbreviation etc.

    During thinking I made the assumption that these are rules. As in systems we could call them business rules. Only when would business rules make some sence in a system? When they are actually executed and most important if the outcome is checked.

    The goal of this sign is the prevent people to park at certain timeslots. If they behave badly and the officer comes around they get a ticket. And here is the missing information: When does the officer comes around? If there is no officer then there will be no ticket and therefor no pain and we could park anytime.

    Related to systems: why should we test business rules if they are not triggered and not controlled?

    Related to the sign: I would start checking if there is an officer. If not then what ever you do, the result will never be a ticket/thow-away of your car.

    If there is an officer, check how what the frquency will be when he does his duty?

    After you did this, make sure he has his ticket book available and not full, or his mobile to call the thow-away car.

    And if all is according the rules, then we might also look at the circumstances. Asume it is your car, only it was stolen and someone else placed it there. Do you have to pay the ticket? You could translate this in testing to a dataware house, which obtained incorrect data from the source. Should you as dataware house pay for the consequences or should the source pay for it by curing the symptoms.

    Perhaps we should as testers think beyond the rules and at a certain point look at the system as an open system, inflected by his environment.

    With regards,


  12. Graham W says:

    Hi Michael… just swinging by after neglecting to do so for a while.  Anyway… this one was a chuckle… definitely a case of "For sale: antique table by old lady with wooden legs"!

    Why stop the interpretations at what the sign has written on it? One can interpret that some group made a policy, and some dept or company makes signs, and some crew had to install it… and after all that who knows if they even got the intended sign in the right spot…

    BTW: "EXCEPT-SUN" — maybe that’s a spelling mistake for "Exception" for HOLs 🙂 (and if think that’s dopey, I actually live near a sign with a spelling mistake, and also one of those "BUMP" markers stencil-painted in 6 foot letters on the road, where the "M" is upside down!)

  13. Jeroen: Hooray to you for looking beyond my question and thinking about whether it needs to be answered at all!

  14. <i> <<Your assignment for this week is to devise as many different interpretations of this sign as you can. Put your answers in the comments below or send them directly to me. I will post my answers (forty of them, plus another seventeen questions) next week, plus also explain what this exercise has to do with testing.>> </i>

    I’d first want to know what you mean by “this sign”. You might be referring to something within the image posted or something else that I could not see which might make me spend time on something that might not be of your interest.

    I’d like to assume that you meant the image that you posted and go ahead brainstorming my interpretations:

    1. It (the image) is indicating a 2 hour parking area where a vehicle owner or driver would be charged for every 2 hours that he/she has parked her vehicle.

    2. The number 2 indicates the second significant board that gives the same information.

    3. “7AM – 6PM” might not be indicating time but instead a restriction of the vehicle registration starting series to be parked in the designated area.

    4. “Except – Sun – Hol” might be indicating a holiday on Sunday on a parking slot

    5. “Except – Sun – Hol” might be indicating an exception to park when there is Sun during a Holiday

    6. “Except by ZONE” might be indicating a time zone that links to “7AM – 6PM”.

    7. 4 might be indicating parking only for four wheeler automobiles and not 2 wheelers.

    8. “Except by ZONE 4 Permit” might be indicating an exception for vehicles that belong to Zone 4 of Seattle to park.

    9. The holes/screws that appear to be above H in “Hour” and below R in “PERMIT” might be indicating the start of the message and end of the message.

    10. The 2 in green background might be indicating a maximum of 2 vehicles to be parked in that designated parking area.

    11. The green line that separates “Except – Sun-Hol” and “Except by ZONE 4 PERMIT” indicates only either of the exception applies.

    12. The different font sizes indicate what is most important and what is least important.

    13. The exception of Zone permit is only by 4 AM/PM

    14. There appears to be dot after SUN in “Except – Sun.-Hol” – which might be indicating that it is not to be read as Sunday but something else that only people in Seattle know.

    15. The message board is written in a way that only people from Seattle understand and it is easy to catch a culprit if he parks his automobile with any other interpretation of the board.

    16. The owner of the parking area might have a name “Sun Hol” and hence he has an exception of parking time.

    17. The 2 in green background might be indicating that it is the second side of the message board and some more exceptions are rules are printed on the other side.

    18. The 2 in green background might be the second side of a 4 sided message board.

    19. Someone might have stuck a sticker on the left top corner with a green background and number 2 printed on it which might be covering some important or unimportant information for the people parking their vehicles.

    20. It indicates a hour parking but there is an exception for people who park between 7 AM to 6 PM apart from Sundays and Holidays

    21. “Except BY” could mean an exception for vehicles that carry “BY” certificate.

    22. The parking area is a Zone 4 permit area.

    23. Maybe this message board was stuck on April 1st to fool people or confuse them about where to park the vehicles.

    24. The 2 in green background could mean for every hour of parking between 7 AM – 6 PM there would be a charge of $2.

    25. The green line that separates “Hour parking 7 AM – 6 PM Except – Sun. – Hol” and “Except Zone by 4 Permit” could mean different exceptions if people want to park in the basement or the first floor where the above rule applies to people who want to park in first floor and below rule applies to people who park in the basement area.

    26. This message board might be mandatory code to be stuck on vehicles to park in some specific area that might be a military zone in Seattle.

    27. [ As you are from Microsoft ]This message board might be in Microsoft’s Seattle office indicating a bug that is known internally at Microsoft and people who get recruited to Microsoft’s Seattle office are briefed during their induction program what that means.

    28. This message board image might be something that Michael Hunter created as an exercise for a tester or to bring in a context to explain something over his blog post.

    <b>What I think might be making this a testing exercise is: </b>

    1. A way to demonstrate ambiguity with test scripts by showing how different testers interpret simple words in too many different ways.

    2. How a simple dot present in “Except – Sun. – Hol” could make a tester think of it as something else than Sunday which was the actual intent (or) How typos impact the understanding of a scripted test or specification document.

    3. How a message that most Seattle or North American people understand is difficult to comprehend for a partner to whom you have outsourced testing business miles away to places like India.

    4. How anyone doesn’t have a control over other’s thought process and hence end users of product might think and try different ways of doing things which a stake holder might not have thought about or might have ignored if it turned out to be a bug.

    5. The power of questioning reveals more information that helps in designing focused tests that yields value.

  15. Last week I asked you to see how many different interpretations of this sign you could devise. After

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