Adding plural to keywords

Question

I am starting to make a hierical keyword sets for my need & wondering where do I add plurals?
Nature
tree
trees
Animals
horse
horses
or
Nature
tree
trees
Animals
horse
horses
Another thing I am thinking is to have multiple keyword catalog for each category, how can this work, when I import any catalog it gets merged with present keyword catalog.
Jesse

Answer 1

From the Controlled Vocabulary web site (http://www.controlledvocabulary.com)
When Writing Keywords
Keep in mind that in most larger online systems, the captions are fully searchable as well, so it may be only necessary to create keywords for those words in the caption that also need plurals, variants and synonyms.
Use plural spelling only, unless the spelling is different than just adding an "s." For example, just using "cats" is sufficient, but if you use "babies" also include "baby."
Use gerunds not verbs. For example, use "running", not "run"
Do not capitalize unless it's the name of a place or a proper noun (most search functions/search engines are NOT case sensitive, but this makes for easier reading).
List alternative spellings for international audience (color / colour, gray / grey, etc.)
In order to copy and paste into the keyword field in Photoshop CS, use a comma and then a space between each term. For example: xxxx, xxx xxxx, xxxxx, term, word phrase, two word phrase, etc. You can can also separate terms using a semi-colon or even a hard carriage return.