What does "Outstation" mean?

Sometimes, when I visit an office, I overhear people using the word "outstation" in these ways:

I will be outstation on Monday and Tuesday, so I will not be able to attend the meeting.

Tomorrow, she will be going outstation.

He is not here. He is outstation.

She is an outstation engineer.

It sounds like "outstation" but it could also be "outstationed". I have not seen it in writing. To me, it sounds like "outstation" (without -ed).

Years ago, my English teacher (from Wales) said that she had never heard the word being used like this. To her, "outstation" means "a remote or outlying station" (Merriam-Webster). It turns out that some people use "outstation" to mean "being away". Interesting use. But is that valid English? It seems that this unusual use of the word "outstation" is mainly concentrated in Singapore, Brunei, Malaysia, and India. Outside of these countries, it appears unlikely that people will understand "I am outstation".

This raises an interesting issue because when new meanings develop, those developments may only be local. English is spoken globally, and if, whether knowingly or not, one uses local meanings, how can one be sure that another person understands one's use of English? The more intelligent the discussion, the more this may be an issue. We need only be aware that some of our words may not be what we intend for them to mean.

“When I use a word,” Humpty Dumpty said, in rather a scornful tone, “it means just what I choose it to mean—neither more nor less.”

“The question is,” said Alice, “whether you can make words mean so many different things.”

“The question is,” said Humpty Dumpty, “which is to be master—that’s all.”

                   - Through the Looking-Glass, Lewis Carroll

In practical terms, I am in favour of sticking to the most common uses. Language is a tool after all, and if no one understands what you say, it is almost as if you have not spoken. Therefore, I will say "I will be away" instead of "I will be outstation". I believe everyone understands what being away is, but I cannot say the same about being outstation.

This demonstrates that there are times when the English language can be difficult. There are so many regional difference and there is no standardization body. There are also a lot of inconsistencies due the heavy borrowing from other languages. This could make it challenging for beginners. It is my opinion that English is easy to learn but exceedingly difficult to master. Native speakers themselves will often male mistakes without even realizing, or even worse, assert that they are right when they are not.