appsweb.cfg or appsweb_$CONTEXT.cfg
This file is defined by environment variable FORMS60_WEB_CONFIG_FILE This is usually in directory $OA_HTML/bin(11i) $INST_TOP/ora/10.1.2/forms/server (R12) on forms tier.
This file is used by any forms client session. When a user try to access forms , f60webmx picks up this file and based on this configuration file creates a forms session to user/client.
<CONTEXT>.env and APPS<CONTEXT>.env
APPS<CONTEXT>.env is main environment file which inturn calls other environment files like <CONTEXT>.env under $APPL_TOP, <CONTEXT>.env under 806 ORACLE_HOME and custom.env for any Customized environment files.
*.dbc file
The .dbc file is mostly used to define database parameters,stands for database connect descriptor file, used to connectto database, it authenticate users against database in FND_USER table.
The .dbc file is actually the database connector descriptor file used to connect to database and this file is by-default located in $FND_TOP/secure directory, this file is quite important as whenever any program likes to connect to database like forms it uses dbc file where there you find the Guest_user_pwd ,when the guest user connect it does not allow it to directly connect to the database but it first connect goes via this file and cross verify the password of the guest which is kept in this file.
DBC file is quite important as whenever Java or any other program like forms want to connect to database it uses dbc file.
httpd.pid and httpd.lock
Apache httpd saves the process id of the parent httpd process to the file logs/httpd.pid .
LockFile
Sets the path to the lockfile used when Oracle HTTP Server is compiled with either USE_FCNTL_SERIALIZED_ACCEPT or USE_FLOCK_SERIALIZED_ACCEPT. It is recommended that default value be used. The main reason for changing it is if the logs directory is NFS mounted, since the lockfile must be stored on a local disk.
For example: LockFile /oracle/Apache/Apache/logs/httpd.lock"