Vahn made a nice notice (a locked post) outlining how the language filters work in general across the gaming platforms. You can find it here:
First and foremost I would like to confirm that Vahn is very correct in stating that the filters that I will discuss bellow belong to Microsoft and not Treyarch. The preceding sentance is now in question due to recent developments see my comments bellow in pinkish color bellow the list of words that is in red.
Clan Tag issues: There are 3 types of known issues in creating a Clan Tag. Language issues, Bad Filter issues, and Gamer Tag issues.
Language issues: The clan tag you have selected is inappropriate. Yes this means that if a reasonable person somewhere can see it as offensive then that is why the filter will not allow it. This also includes Clan Tags that you create that put together with your Gamer Tag create an offensive word or phrase.
Bad Filter issues: There is a known bug with the filter where the filter has picked random words that are not offensive and has flagged them as offensive. It has been reported that this list of words is growing rapidly on a daily bases and the most recent case was reported 9-12-2011. This has not yet been confirmed. The bellow list (in the Gamer Tag issue section) includes words that are larger than the Clan Tag feature will allow (4 maximum charicters) so only the words that are 4 charicters or less apply to this section/particular issue.
Gamer Tag issue: Those with this issue will not be able to create any clan tag at all because of an issue the filter has with your Gamer Tag. Any clan tag attempted including ones known to pass the filter ok (ones that others are currently using) result in the same error message every time, "clan name denied due to prohibited text". Chances are that you are not entering "prohibited text" (though it is possible) rather those with this issue are getting that error because the filter is checking to make sure that the clan tag you are attempting does not combine with your Gamer Tag to create a bad word. However it is seeing a word in your Gamer Tag that is already thinks is bad (see the list bellow) so it never gets to the point where it checks the Clan Tag you are trying and just gives you the above quoted error. Because the list of words seems to be growing, the list of people affected by this would logically be exponentially growing as multiple Gamer Tags use the same words (I bet when the letter "j" was added the number of gamers affected spiked very quickly)
Here is a list of known words that are not offensive that are confirmed to be affected by this bug:
assault (this was the first red flag as the basic idea behind this was that the "ass" in the word "assault" was what was catching the filter. However I have had a very difficult time find any other word that contains the word "ass" in it to be flagged as offensive by this filter including the word "assault1". That made it clear that this word was added to the list as a mistake/bug/error/glitch, whatever you want to call it, along with the following words)
midnight
beast
jersey
crab
ib
lb
j <---- yes the letter "j" .....yeesh
gold
lady
ia
jagriff333
man 198
man 196
man 193
n 19
f1
fabulous
blame
is permitted (ironically is not permitted....
)
acid
piss (potty talk could fit in as offensive to be honest but I am including it as it changed recently making it fit the broken part of the profile for this filter)
18
land
I have been monitoring an exponential increase in the number of gamers affected by bug portion of the filter. The inconsistancy of information and facts is increasingly putting into question who is actually responsible for why folks are not able to use the clan tag feature at all. This is what I know:
I can use the create a clan tag feature in COD4 and MW2 (right now today), but I can not use the exact same feature in COD:BO. Why is that?
Many gamers are reporting that they are only becomeing affected by inability to use the clan tag feature at all be cause of words/letters/numbers in their Gamer Tags that have only been added to the list of filtered words since the last patch released by Treyarch. This implies that Treyarch is directly responsible. It may be that it is Microsofts filter but the implication of the filter, or the coding done by Treyarch to comply with using the filter is what is causing the issues. That would explain why I can use the same feature right now today in COD4 and MW2 but not in Black Ops.
I am not able to get any info at all from Microsoft as they will not talk about it at all and I am not able to determine who to talk to at Microsoft. I have only been able to determine that ALL the public resources at Microsoft do no know who is responsible for the filter and do not know how to troubleshoot issues with the filter.
Custom Class Name issues: For those who do not know, you can save custom class to custom game types and upload them to your fileshare for others to download and use. This allows them to see what you name your classes. For that reason Custom Class Names must go through the filter. Some gun names such as "FAMAS", "Galil" or "SPAS-12" are not allowed. This is likley due to copywrite or tradmark on those names (not confirmed). The only other known issues with this are the exact same as “Bad Filter issues†and “Language issues†listed above for Clan Tags.
Unable to create any Clan Tag at all: See “Gamer Tag Issues†above.
Now it is possible, and the latest title update for this game dated 9/13/2011 suggests it, that Treyarch is able to add a second layer of filtering on top of what Microsoft does. This allows them to ban offensive clan tags that the Microsoft filter allows (there are many). The way to check this is by following the following steps:
1. Attempt to create a clan tag
2. Clan tag is denied "due to prohibited text"
3. Erase what you have in your xbox live gamer card profile in the Moto section and replace it with what you tried to use as a clan tag.
4. If it allows you to post it in your Moto then it is Treyarch that is denying the it's use as a clan tag. If not then the Microsoft filter is to blame.
For those who are unable to create a clan tag and none of the words in the above list are contained in your Gamer Tag, this is how to find out what in your GT is causing the filter to flag your GT:
Attempt to create a classname with parts of your GT untill you find what part is getting caught in thne filter.
EX: For my GT "ISSI Midnight" I first tried "ISSI" that worked ok so I then tried "midnight" that did not work. So I know that the word "midnight" in my GT is what is getting caught in the filter. I then tried "idnight" that let me know that it is the full word and not part of the word that is getting caught in the filter. I did that becuase some people thought that the word "nig" contained inthe word "midnight" is what was getting caught. That was not the case for me.
I am creating this as there are so darn many threads popping up that are filter related. Also the number of folks being affected by the above issues appears to be increasing lately. My hope is to get this stickied to limit the number of threads being created on the same issues.
http://www.callofduty.com/board/viewtopic.php?f=70&t=451683
Unfortunately his information was not entirely correct (the "ass" in "assault" is not why that word is caught in the filter as proved by the fact that the word "assault1" works just fine) and is not as complete as the information I have gathered for you all bellow. I am not trying to dog the guy. The infomation in is post propelled my research into the filter greatly and I am very thankful for his post.First and foremost I would like to confirm that Vahn is very correct in stating that the filters that I will discuss bellow belong to Microsoft and not Treyarch. The preceding sentance is now in question due to recent developments see my comments bellow in pinkish color bellow the list of words that is in red.
Clan Tag issues: There are 3 types of known issues in creating a Clan Tag. Language issues, Bad Filter issues, and Gamer Tag issues.
Language issues: The clan tag you have selected is inappropriate. Yes this means that if a reasonable person somewhere can see it as offensive then that is why the filter will not allow it. This also includes Clan Tags that you create that put together with your Gamer Tag create an offensive word or phrase.
Bad Filter issues: There is a known bug with the filter where the filter has picked random words that are not offensive and has flagged them as offensive. It has been reported that this list of words is growing rapidly on a daily bases and the most recent case was reported 9-12-2011. This has not yet been confirmed. The bellow list (in the Gamer Tag issue section) includes words that are larger than the Clan Tag feature will allow (4 maximum charicters) so only the words that are 4 charicters or less apply to this section/particular issue.
Gamer Tag issue: Those with this issue will not be able to create any clan tag at all because of an issue the filter has with your Gamer Tag. Any clan tag attempted including ones known to pass the filter ok (ones that others are currently using) result in the same error message every time, "clan name denied due to prohibited text". Chances are that you are not entering "prohibited text" (though it is possible) rather those with this issue are getting that error because the filter is checking to make sure that the clan tag you are attempting does not combine with your Gamer Tag to create a bad word. However it is seeing a word in your Gamer Tag that is already thinks is bad (see the list bellow) so it never gets to the point where it checks the Clan Tag you are trying and just gives you the above quoted error. Because the list of words seems to be growing, the list of people affected by this would logically be exponentially growing as multiple Gamer Tags use the same words (I bet when the letter "j" was added the number of gamers affected spiked very quickly)
Here is a list of known words that are not offensive that are confirmed to be affected by this bug:
assault (this was the first red flag as the basic idea behind this was that the "ass" in the word "assault" was what was catching the filter. However I have had a very difficult time find any other word that contains the word "ass" in it to be flagged as offensive by this filter including the word "assault1". That made it clear that this word was added to the list as a mistake/bug/error/glitch, whatever you want to call it, along with the following words)
midnight
beast
jersey
crab
ib
lb
j <---- yes the letter "j" .....yeesh
gold
lady
ia
jagriff333
man 198
man 196
man 193
n 19
f1
fabulous
blame
is permitted (ironically is not permitted....


acid
piss (potty talk could fit in as offensive to be honest but I am including it as it changed recently making it fit the broken part of the profile for this filter)
18
land
I have been monitoring an exponential increase in the number of gamers affected by bug portion of the filter. The inconsistancy of information and facts is increasingly putting into question who is actually responsible for why folks are not able to use the clan tag feature at all. This is what I know:
I can use the create a clan tag feature in COD4 and MW2 (right now today), but I can not use the exact same feature in COD:BO. Why is that?
Many gamers are reporting that they are only becomeing affected by inability to use the clan tag feature at all be cause of words/letters/numbers in their Gamer Tags that have only been added to the list of filtered words since the last patch released by Treyarch. This implies that Treyarch is directly responsible. It may be that it is Microsofts filter but the implication of the filter, or the coding done by Treyarch to comply with using the filter is what is causing the issues. That would explain why I can use the same feature right now today in COD4 and MW2 but not in Black Ops.
I am not able to get any info at all from Microsoft as they will not talk about it at all and I am not able to determine who to talk to at Microsoft. I have only been able to determine that ALL the public resources at Microsoft do no know who is responsible for the filter and do not know how to troubleshoot issues with the filter.
Custom Class Name issues: For those who do not know, you can save custom class to custom game types and upload them to your fileshare for others to download and use. This allows them to see what you name your classes. For that reason Custom Class Names must go through the filter. Some gun names such as "FAMAS", "Galil" or "SPAS-12" are not allowed. This is likley due to copywrite or tradmark on those names (not confirmed). The only other known issues with this are the exact same as “Bad Filter issues†and “Language issues†listed above for Clan Tags.
Unable to create any Clan Tag at all: See “Gamer Tag Issues†above.
Now it is possible, and the latest title update for this game dated 9/13/2011 suggests it, that Treyarch is able to add a second layer of filtering on top of what Microsoft does. This allows them to ban offensive clan tags that the Microsoft filter allows (there are many). The way to check this is by following the following steps:
1. Attempt to create a clan tag
2. Clan tag is denied "due to prohibited text"
3. Erase what you have in your xbox live gamer card profile in the Moto section and replace it with what you tried to use as a clan tag.
4. If it allows you to post it in your Moto then it is Treyarch that is denying the it's use as a clan tag. If not then the Microsoft filter is to blame.
For those who are unable to create a clan tag and none of the words in the above list are contained in your Gamer Tag, this is how to find out what in your GT is causing the filter to flag your GT:
Attempt to create a classname with parts of your GT untill you find what part is getting caught in thne filter.
EX: For my GT "ISSI Midnight" I first tried "ISSI" that worked ok so I then tried "midnight" that did not work. So I know that the word "midnight" in my GT is what is getting caught in the filter. I then tried "idnight" that let me know that it is the full word and not part of the word that is getting caught in the filter. I did that becuase some people thought that the word "nig" contained inthe word "midnight" is what was getting caught. That was not the case for me.
I am creating this as there are so darn many threads popping up that are filter related. Also the number of folks being affected by the above issues appears to be increasing lately. My hope is to get this stickied to limit the number of threads being created on the same issues.