diff --git a/rds-postgres/variables.tf b/rds-postgres/variables.tf
index d7c1cde..3240eb8 100644
--- a/rds-postgres/variables.tf
+++ b/rds-postgres/variables.tf
@@ -1,23 +1,56 @@
+#---
+# change between different modules as needed
+#---
+variable "name" {
+  description = "Security Group Name"
+  type        = string
+  default     = "rds-postgres"
+}
+
+variable "description" {
+  description = "Security Group Description"
+  type        = string
+  default     = "RDS Postgres Security Group"
+}
+
+variable "short_description" {
+  description = "Security Group Short Description"
+  type        = string
+  default     = "Postgres"
+}
+
+variable "enable_self" {
+  description = "Enable|Disable self full access"
+  type        = bool
+  default     = false
+}
+
+variable "use_vpc_cidr" {
+  description = "Enable|Disable use of VPC CIDR block in the ingress_networks"
+  type        = bool
+  default     = false
+}
+
+#---
+# others with defaults
+#---
 variable "vpc_id" {
   description = "VPC ID Number"
   type        = string
 }
 
+data "aws_vpc" "selected" {
+  id = "${var.vpc_id}"
+}
+
 variable "vpc_full_name" {
   description = "VPC Name"
   type        = string
   default     = ""
 }
 
-variable "name" {
-  description = "Security group Name"
-  type        = string
-  #  default = "m-rds-postgres"
-  default = "m-postgres-db"
-}
-
-variable "networks" {
-  description = "List of ingress networks (applies to all ports)"
+variable "ingress_networks" {
+  description = "List of ingress networks for external access (not all ports)"
   type        = list(string)
   default     = ["0.0.0.0/0"]
 }
@@ -28,6 +61,18 @@ variable "egress_networks" {
   default     = ["0.0.0.0/0"]
 }
 
+variable "ingress_security_groups" {
+  description = "List of ingress security groups for all ports"
+  type        = list(string)
+  default     = []
+}
+
+variable "egress_security_groups" {
+  description = "List of egress security groups (all ports)"
+  type        = list(string)
+  default     = []
+}
+
 variable "tags" {
   description = "Extra security group tags"
   type        = map