Oracle file https://docs.oracle.com/cd/E26401_01/doc.122/e22952/T156458T659606.htm lists schemas names of Oracle EBS. But, some schemas became obsolete in R12.
EBS schema names must be in table FND_ORACLE_USERID and EBS user name must appear in table FND_USER.
All below schema owners are not in table FND_ORACLE_USERID in my R12.1.3 instances. It is safe to change their password by alter statement, such as "alter user ABM identified by new_Pwd;", while FNDCPASS will give error APP-FND-02702: ABM is not a valid oracle user because FNDCPASS utility and ALLORACLE functionality were designed for valid applications users/schemas.
SELECT ORACLE_ID, ORACLE_USERNAME, CREATION_DATE,LAST_UPDATE_DATE,ENABLED_FLAG,DESCRIPTION
FROM apps.FND_ORACLE_USERID
WHERE ORACLE_USERNAME IN (
'ABM',
'AHM',
'AMF',
'CSS',
'CUE',
'CUN',
'EAA',
'EVM',
'FPT',
'IBA',
'IMT',
'IPD',
'ME',
'OKB',
'OKO',
'OKR',
'OZP',
'OZS',
'RHX',
'RLA',
'VEH',
'XNC',
'XNI',
'XNM',
'XNS',
);
