# Specific Grammar Rules in Regards to Specific Words or Phrases

The following grammar rules are meant to distinguish when and how to use specific words or which form of a word to use in particular situations:

"a" vs. "an"
  Description: This is one of the most common errors made in English writing. There is a common misperception that the rule is that you use "a" before words that start with a consonant and "an" before words that start with a vowel. However, that is only partially correct. REMEMBER, it is how the subsequent word SOUNDS, not how it is written. The letters 'H' and 'U' usually cause the most confusion because some words that start with those letters have a consonant sound and some have a vowel sound.

  Rule to follow: The rule is that you use "a" before words that start with a consonant SOUND and "an" before words that start with a vowel SOUND.

  Examples for "a": "Unique" or "URL" - You would use "a'" before both words because they both begin with a 'you' SOUND. "Historic" or "High" - You would use "a'" before them because they begin with a consonant 'h' SOUND.

  Examples for "an": "Unusual" or "Umbrella" - You would use "an'" before both words because they both begin with an 'uh' SOUND. "Hour" or "HTTP" - You would use "an'" before them because they begin with an 'a-wer' and 'aye' SOUND, respectively.

"Such as" vs. "Like"
  Description: This is another one of the most common problems found in English writing. Many grammarians consider both to be acceptable, especially when speaking, but when using them in technical writing, you should not use them interchangeably because they have different implications. "Like" suggests comparison (something is similar to something else), while "such as" implies inclusion (something is precisely included as an example of something).

  Rules to follow: In most cases, avoid using "like" when you can use "such as" instead, and only use "like" when making some sort of comparison to something similar.

  Example of "such as": You can specify a set of transformation scenarios to convert XML documents to various formats, such as HTML and PDF.
  Note: When "such as" is part of a non-restrictive clause, as it is in the above example, it needs to be preceded with a comma (or the whole clause placed in parentheses).

  Example of "like": A DITA book map is intended for creating output that is like a book.

"That" vs. "Which"
  Description: There are some experts who believe this is more of a style choice than a grammar rule, but those people are completely ignoring the fact that when these two words are used interchangeably they are usually two completely different types of grammatical words ("that" being an adjective in these instances, and "which" being a pronoun/determiner). Some people might also argue that the rules are more complex and flexible than the rules we will use, but it is important to keep the rules simple and for the purposes of our User Guide, we use these two words in ways that are only grammatically correct and clear if we follow the rules listed below. Also, in most cases, it looks and sounds much better to use this common grammar rule.
  Note: It becomes even more complex and confusing when considering combination of words such as "for which" or "in which". They are sometimes used instead of "that" to prevent ending a sentence with a preposition. However, that becomes a completely different subject and this rule should not be used for those instances. The word "which" is also used in multiple ways, some of which are not interchangeable with "that" (for example, "determine which one to use"). To make it as simple as possible, just use this rule to determine when to use the single words "that" or "which" when they could be used interchangeably.
  Rules to follow: To make a complex topic as simple as possible, use "that" before a restrictive clause and "which" before a non-restrictive clause.
  - A restrictive clause is part of a sentence that you can not get rid of because it specifically restricts some other part of the sentence and without it the meaning of the sentence would change (or the sentence would be incomplete).
  - A non-restrictive clause is something that can be left off without changing the meaning of the sentence (or making it incomplete) and it is simply additional information.
    Important: Non-restrictive clauses are almost always surrounded by, or preceded by, commas. Therefore, whenever you use "which" before a non-restrictive clause, it should be preceded with a comma.

  Example of an improper use of "that": This section lists and describes all the contextual menu actions that are also available in various submenus. [You should not use "that" in this instance because the reader might understand that the section only lists the actions that are in both locations instead of understanding that the section includes ALL the contextual menu actions (and that they are ALSO available in submenus). The clause that follows "that" in this case is a non-restrictive clause that simply provides additional information. Therefore, you should use ", which" in this type of instance.

  Example of a proper use of "that": This section explains the actions that are available for a Berkeley DB XML connection. [The clause that follows "that" cannot be omitted without causing an incomplete sentence and it does not simply provide additional information (it is essential to the meaning of the sentence). Therefore, it is a restrictive clause and you must use "that" instead of "which"].

  Example of an improper use of "which": The stylesheet contains templates which output the static header and footers for various parts of the PDF. [You cannot use "which" in this case because the information that follows it is essential to the meaning of the sentence and is not simply providing additional information. In this case, you would need to use "that" instead.]

  Example of a proper use of "which": While you are working on your own branch, other team members can continue to make important changes in the parent branch, which could be the trunk itself or any other branch. [The clause that follows "which" could be omitted without changing the meaning of the sentence since it simply provides additional information and could even be an independent idea of its own (for example, by changing "which" to "It" and making it a new sentence.]

"That" vs. "Who"
  Description: This can be tricky and complicated, but to make it as simple as possible, consider who or what is being described. Some experts say that it is acceptable to use either word when describing a person, but it seems to dehumanize the person when using "that" to describe a person.

  Rule to follow: Use "that" when describing an object, or "who" when describing a person.

  Example of "that": Permanent reassignment of a Named User to a position that does not involve the use of the Software.

  Example of "who": Permanent reassignment of a Named User who owns the rights to the software.

"To either" vs. "Either to"
  Description: This is one of those rules that differ depending on whether you are speaking or writing. Both phrases mean exactly the same thing and when speaking, both phrases are acceptable. However, when writing, "to either" is simply MORE grammatically correct.

  Rules to follow: As a general rule, it is better to use "to either" since the word "either" implies a choice of two options and by placing the "to" in the front, you are removing it from the grammatical construction 'either A or B'. If you do use "either to", you would need to include a second "to" to make the construction grammatically correct ('either to A or to B').

  Example of "either to": You can use this API either to print the document or to show the Print Preview dialog box. [To make this sentence grammatically correct, notice that you have to use a second "to" in front of the second clause.]

  Example of "to either": You can use this API to either print the document or show the Print Preview dialog box.. [Notice that by using "to either" you do not need a second "to" before the second clause to make the sentence grammatically correct.]

"Affect" vs. "Effect"
  Description: These two words are often confused when referring to something changing another thing. The word "effect" is a noun, while "affect" is a verb.

  Rules to follow: Basically, use "Effect" when referring to the change itself (noun), and "Affect" when referring to the act of changing (verb).

  Example of "effect": Documents that contain long lines can have a negative effect on performance.

  Example of "affect": Documents that contain long lines can affect performance.

"Between" vs. "Among"
  Description: This rule can be confusing, but you simply need to think about whether or not the referenced things are clearly separated.

  Rules to follow: Use "between" when referring to multiple things that are clearly separated, and "among" for things that you can cannot clearly separate because they are part of a group of objects.

  Example of "between": The DITA Maps Manager organizes the relationships between maps and topics.

  Example of "among": DITA maps organize the relationships among various topics.

"Different" vs. "Various" or "Multiple"
  Description: Misusing the word "different" is one of the most common problems in formal and technical writing. When speaking, or perhaps in colloquial writing, the two words are often used synonymously, but in formal or technical writing it is important to differentiate between the two. "Different" implies a comparison (different from what?), whereas "various" or "multiple" implies multiplicity or diversity.

  Rules to follow: Do not use "different" when you mean "various" or "multiple" ("other" and "another" are also examples of words that might be better). Only use "different" to refer to comparison or distinction between things. Also, if you are to use the word "different", stop and ask yourself "it is different from what?" If you cannot answer that question or it does not make sense, avoid using "different".

  Example of "different": The name of the directory might be something different on your system.

  Example of "various": The Quick Fix support helps you resolve various errors that appear in documents.

"However" vs. "But" vs. "Although"
  Description: These three words are often misunderstood in English writing and many people incorrectly think they are completely synonymous. While their meanings are very similar, "however" and "but" introduces a contrast or contradiction to a previous statement, while "although" does not necessarily imply contrast and can be used if both statements could be true. Also, "but" and "although" are conjunctions, while "however" is an adverb and needs to be used differently in the sentence structure.
  Rules to follow: To make it as simple as possible, follow these rules for each word:
  - "However" - When using "however", in most cases it should begin a new sentence and be followed by a comma. Use it when you want to stress contrast or contradiction AND you want to start a new sentence (therefore contrasting the two sentences).
  - "But" - When using "but", do not ever use it to start a new sentence and it needs to be preceded by a comma. Use it when you want to stress contrast or contradiction AND you do not want to start a new sentence (therefore contrasting the two parts of the same sentence).
  - "Although" - This word may be used to start a sentence or in the middle of a sentence. When using it to start a new sentence it would not be followed by a comma. When using it in the middle of a sentence it needs to be preceded by a comma. Use it when you want to stress that both parts of the statement may be true (make sure both parts of the statement are included in the sentence).

  Example of "however": He knows a lot about general programming. However, he has some confusion about Java programming.

  Example of "but": She said the book is blue, but I think it is green.

  Examples of "although": We usually speak in Romanian, although sometimes we use English. OR Although we usually speak in Romanian, sometimes we use English.

"Less" vs. "Fewer"
  Description: Despite popular belief, there is a clear difference between when these two words should be used in most cases.

  Rules to follow: Use "less" for things that are not quantifiable, and "fewer" for things that you can clearly count.

  Example of "less": It uses less memory.

  Example of "fewer": It uses fewer than 300 MB.

"Whether" vs. "Whether or not"
  Description: There are so many conditions to this rule that it seems that many modern writers have decided that it is too complicated and not worth their time to consider so they simply ignore all of them and never include "or not" even when doing so leads to ambiguity. They justify this by suggesting that the "or not" is implied when appropriate and is therefore optional. However, this is clearly not always the case. Your meaning can easily become unclear or ideas might seem incomplete if you omit "or not" in many cases. In the very least, it might irritate your reader if they have to pause and re-read the sentence, and its surrounding sentences, to decipher the intended meaning.
  Consider the following example: Oxygen prompts you to choose whether you want to paste the content as XML. The intended meaning could have been any of the following:
  - Oxygen prompts you to choose whether you want to paste the content as XML or paste it as something else (such as text). [In this case, the sentence and idea is incomplete and you need to specify what that 'something else' is.]
  - Oxygen prompts you to choose whether you want to paste the content as XML, or not at all. [In this case, it is imperative to use whether or not to avoid breaking the flow and possible ambiguity.]
  - Oxygen prompts you to choose something (that was previously mentioned), regardless of whether or not you want to paste the content. [In this case, you would need a commas after choose and use whether or not or regardless of whether or not.]

  Rules to follow: Consider the following rules when using the word "whether":

  - If you are differentiating between whether to do something, or to not do something entirely, always use "whether or not".
  - If you are differentiating between two different things, use "whether" and specify both things.
  - In situations where "or not" might be considered optional, it is far better to include it than to omit it. Remember to make sure the meaning of the sentence is clear and that it will not require the reader to stop and re-read it simply because you left out a few extra words that would make it more clear.
  - In some cases, it might be better to simply use some sort of "if" statement instead.
  - Whenever the use of the word "whether" is synonymous to regardless of whether or not, you must use "whether or not" or "regardless of whether or not".

  Example of "whether": Oxygen prompts you to choose whether you want to paste the content as XML or plain text.

  Example of "whether or not": Oxygen prompts you to choose whether or not you want to paste the content.