I have a spec that says a particular field will be alpha-text, right-padded with spaces to be 10 characters long, and I want to capture the alpha-part of the match.

This expression captures the entire section:

```
"([[:alpha:][:s:]]{10})"

```

However, I only want to capture the alpha-part, and still match (but not capture) on the remaining white-space. So if the alpha is 3-characters long, the next match needs to 7 white-spaces.

How can I do this?