How do I use the env_file directive in Docker Compose properly?

I'm trying to organize my environment variable files for Docker Compose by separating them instead of using one large .env file. My plan is to have two files for each area: a 'common' file and a specific file. In this example, I have two files: .env.common and .env.main, but no .env file. However, when I try to start my containers, I'm getting ambiguous warning messages. Here's my `compose.yaml` setup:

```
services:
hello-main:
image: hello-world
env_file:
- .env.common
- .env.main
environment:
- TZ=${TZ}
- APPDIR=${APPDIR}
- PUID=${PUID}
- PGID=${PGID}
- FOOBAR=${FOOBAR}
- ZONE=example.com
```

The .env.common file contains variables common to every area:

```
TZ="America/New_York"
APPDIR=/home/docker/dockerservice
PUID=1000
PGID=1000
```

And .env.main has just a specific value:

```
FOOBAR=172.16.68.8
```

When I run the containers, I see warnings like:

```
WARN[0000] The "TZ" variable is not set. Defaulting to a blank string.
WARN[0000] The "APPDIR" variable is not set. Defaulting to a blank string.
WARN[0000] The "PUID" variable is not set. Defaulting to a blank string.
WARN[0000] The "PGID" variable is not set. Defaulting to a blank string.
WARN[0000] The "FOOBAR" variable is not set. Defaulting to a blank string.
```

It seems like neither the .env.common nor .env.main files are being utilized by the env_file directive. What might I be doing wrong? Also, I've updated my configuration based on some community suggestions, where I learned that I might not need the environment section unless I'm overriding values. So now it looks like this:

```
environment:
# - TZ=${TZ}
# - APPDIR=${APPDIR}
# - PUID=${PUID}
# - PGID=${PGID}
- FOOBAR=my_foobar # override ${FOOBAR}
- ZONE=example.com
```

Can someone help clarify what's going wrong?