is vs may be

In this particular case, "is" and "may be" can be used interchangeably. By the way, in the United States, it is spelled "ma'am." Ma'am is a contraction of "madam," and I believe that in Britain, it is only used when addressing the Queen, and only after first addressing her as "Your Majesty." Our British English speakers can comment on that.

In the United States it is used as a respectful form of address toward women, usually when addressing a woman thought to be older than the speaker; when a sales clerk or person in a similar station is addressing any woman; and in certain regions, it is used as the almost exclusive form of address to a woman unknown to the speaker. It is also used as a form of address in the military for any woman know to outrank the speaker.

Addressing an unknown woman as "Lady" is a not too subtle way of saying that the woman in question is annoying to the speaker. OK, Lady, whatever you say. If the woman in question responds by saying: "Fine!"--then you know you are in deep trouble.

I wonder if tanguatlay is talking about the casual, affectionate way that children might address their mothers in the UK. There are regional variations. Southerners usually say 'Mum', around the West Midlands they say "Mom", and in certain parts of the North (and in Wales), "Mam" is common. Certainly the example usage given ("Hey Mam") makes me think this, especially with 'Mam' being capitalised. You wouldn't say "Hey ma'am" to the Queen, or a superior female military or police officer, any more than you would say "Wassup ma'am!" or "Yo ma'am!". That is, you wouldn't mix a deeply casual and informal register with a respectful formal one.

To answer what (I think) is tanguatlay's question:

It seems that "Mam" may be a possible spelling in the US.
This sentence expresses two levels of tentativeness (seems... may be) about a possibility.

It seems that "Mam" is a possible spelling in the US.
This sentence expresses one level of tentativeness (seems) about that possibility.

At a guess, 'ma'am' is how it's written, but it sounds like mam. I've never figured out why it's that way, but that's how it seems to be. American, of course.

As a polite form of address to a female stranger, 'ma'am' is mainly American, I agree, but it is used in British situations such as the military and police where 'sir' would be used if the person addressed were male, say when a person of lower rank addresses a senior NCO or officer. It does strike me as odd when American tourists in England address me as 'sir' when asking for directions.

Mostly, I was remarking on what I think is a big difference between the spelling and the pronunciation.

As for being addressed as sir; I bet it drives you up the wall when the same Americans will say "Thank you, sir" to a waiter in a restaurant.

There is no difference between the British and US spellings of 'ma'am', the polite form address for females, however I believe the US pronunciation rhymes with 'ham' or 'slam' whereas the British pronunciation rhymes with 'harm' (mostly pronounced non-rhotically).

Thanks to all of you.

Tang not quite sure whacha mean by that q

The use of ma'am varies around the US. It can become kind of muddled re who to say it to, and the connotation.

Caveat, this is all from my personal observation having lived in various regions in the US. I've lived in the NE, South, Mid West and briefly in the North West.

The further South you go, the more the use of ma'am increases, and not just with addressing women who are strangers.

I'm gong to be 58 next week, have lived in an urban area of Texas for about 20 years, and in the South in general. I want people I don't know, who are trying to get my attention, to call me Ma'am. It's respectful, but friendly at the same time. I definately do not want someone to call me Miss. At my age, that's ridiculous. It's especially amusing when someone half my age or less calls me "Miss". They usually seem hesitant about this, not quite knowing what to do. On quite a few occassions I'll gentle correct them, and say "That would be Ma'am.
I call anyone from the age of 25 up Ma'am myself, when trying to get their attention.

The further into rural areas you go, the more the use increases, especially in young people, who have been taught to address their elders that way.
Much in the way as when I was being raised as a Yankee child, I would never have dared to call an adult by their first name, unless they were the most intimate of family friends. It was always Mrs. Harrision, Mr. Jenkins. Unfortunately, I never get called Mrs. Tea, and that's a shame.

When they are 70 or so and above, I'll address them as Ma'am in other ways too. Mainly as "Yes Ma'am" in a low low deferential way when they have said practically anything to me. Once they are 85 or 90 or above, they get the full Ma'am treatment, preferring that over assuming someone that senior to me would want me to use their first name. Believe me, in Texas or other parts of the South, I've never been corrected by one of these Wise Elders. I also call elderly men sir. It's respectful.

In the South, it can also be used to replace "excuse me?" if you say it with the intonation of a question....Ma'am? Or Sir?

Another delightful custom, and a way to get around calling a woman older than you, is to to throw "Miss" in front of the first name. I know this seems contradictory to what I said about about using "Miss", but while calling me Miss at my age is silly, calling me Miss Chai is both friendly and respectful. I can totally call a 90 year old "Miss Edna" and have it appreciated.

Now, in the North, especially the NE, many women bristle at Ma'am, thinking the person saying it is calling them old. I think that's sad personally, as being called Ma'am is a sign of having reached a level of maturity and respectability.