Parallelism
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Parallelism refers to the correct use of stem sentences or clauses with collections of sentences that can be thought of as being read 'in parallel' - typically in lists.
Parallelism in text
The most common place where parallelism is incorrectly used within text, is in an 'either/or' or 'both/and' clause. As a check, it should be possible (for example) to remove both the words 'either' and 'or' and one clause, and the remaining text still make grammatical sense (and for the same to be true with the second clause).
Examples:
| Incorrect | Correct |
|---|---|
| Prices can be defined either at the Merchandise Category level or the article level. | Prices can be defined either at the Merchandise Category level or at the article level. |
Using the rule of thumb given above, we would split the leftmost (incorrect) sentence as follows (delineated by horizontal bars [|]):
Prices can be definedeither| at the Merchandise Category levelor| the article level.
This would give two separate (parallel) sentences of:
- Prices can be defined at the Merchandise Category level.
- Prices can be defined the article level.
In the second sentence we are missing an 'at'. Compare this to the rightmost (correct) sentence, split the same way:
Prices can be definedeither| at the Merchandise Category levelor| at the article level.
This would give two separate (parallel) sentences of:
- Prices can be defined at the Merchandise Category level.
- Prices can be defined at the article level.
Both of these are grammatically correct, so this is clearly the correct use of parallelism. Note that the following construct would also be a valid use of parallelism:
Prices can be defined at either the Merchandise Category level or the article level.
Parallelism in lists
It must be possible to combine each clause in the list with the stem sentence (and without adding to or removing words from either one), to form a complete, valid sentence.
Examples:
| Incorrect | Correct |
|---|---|
Before the order can be saved, the system checks that:
| Before the order can be saved, the system checks that:
|
Some guides recommend that all duplicated words should be placed in the stem sentence and not the following clauses. However, this can sometimes appear awkward. It is therefore better to split the stem sentence and clause at a logical break (usually by whole clause).
Parallelism in tables
Particularly in user instructions, tables can be considered in the same way as lists, and the same rules of parallelism should be used. The column headings would form the stem sentences, and the cells below this are the following clauses. The guideline here is that when read as a complete sentence, the column headings and the clauses the cells for a single row should form a complete sentence.
Examples:
| Incorrect | Correct | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Enter the customer type in the CsTy field, as follows:
| Enter the customer type in the CsTy field, as follows:
|
If the first option in the rightmost example is read as a sentence, it becomes "If the customer is | a third-party customer | then | enter 01" (pipes added to show breaks) which is grammatically correct.
Note that each column heading is followed by an ellipsis (...) to emphasize that this is a stem sentence. The 'IF' and 'THEN' have been placed in upper-case to emphasize that the reader needs to make a choice.
