im assuming you want config variables rather than php variables (php variables have a scope in which you can use them) when reading your post
here are all the config variables (the variables come from the admin and i think the provider section as well im not sure) for 4.1.6 (4.x should work for the most part as well)
Code:
name value category
acct_coupon_discount Sales:Coupon Discount QuickBooks
acct_discount Sales:Discount QuickBooks
acct_gc Sales:Gift Certificate QuickBooks
acct_gc_discount Sales:Gift Certificate Discount QuickBooks
acct_inv_asset Inventory Asset QuickBooks
acct_inv_cogs Cost of Goods Sold QuickBooks
acct_product Sales:Product QuickBooks
acct_shipping Sales:Shipping QuickBooks
acct_tax Website:Tax QuickBooks
active_subscriptions_processor
add2wl_unlogged_user Y Wishlist
additional_fields User_Profiles
admin_sqlerror_notify N Email_Note
allow_auto_create_categories Y Import_3x_4x
allow_customer_select_tpl Y Gift_Certificates
allow_ips Security
allow_search_by_words Y General
allow_update_quantity_in_cart Y Appearance
allow_user_modify_tax_number N Taxes
alter_currency_rate 0.87 General
alter_currency_symbol € General
anti_fraud_license Anti_Fraud
anti_fraud_limit 5 Anti_Fraud
anti_fraud_order_limit 500 Anti_Fraud
apply_default_country N General
ARB_account Shipping
ARB_id Shipping
ARB_password Shipping
ARB_shipping_key Shipping
ARB_shipping_key_intl Shipping
ARB_testmode Y Shipping
bestsellers_menu Y Bestsellers
bestsellers_thumbnails Y Bestsellers
blowfish_enabled N Security
buynow_button_enabled Y Appearance
buynow_with_options_enabled N Product_Options
card_types a:12:{i:0;a:3:{s:4:"code";s:4:"VISA";s:4:"type";s:...
check_cc_number N General
check_zero_order Y Anti_Fraud
cmpi_currency USD CMPI
cmpi_enabled N CMPI
cmpi_merchantid CMPI
cmpi_proseccorid CMPI
cmpi_url https://centineltest.cardinalcommerce.com:443/maps... CMPI
company_fax 1-800-555-5555 Company
company_name Your Company Name Company
company_phone 1-800-555-5555 Company
company_phone_2 500-555-5555 Company
company_website www.x-cart.com Company
compiled_tpl_check_md5 Y Security
contact_us_fields Contact_Us
count_products Y Appearance
CPC_merchant_id Shipping
crypt_method Security
currency_symbol $ General
customer_reviews Y Customer_Reviews
customer_voting Y Customer_Reviews
data_cache_expiration 1178703807
date_format %d-%m-%Y Appearance
db_backup_date
default_admin_language US
default_city New York General
default_country US General
default_customer_language US
default_giftcert_template template_default.tpl Gift_Certificates
default_pwd Y General
default_state NY General
default_zipcode 10001 General
det_image_popup N Detailed_Product_Images
det_image_popup_js_based N Detailed_Product_Images
disabled_languages
disable_anonymous_checkout N General
disable_cc Y General
disable_outofstock_products N General
disable_shipping Y Shipping
disallowed_file_exts phtml, php3, php, pl, cgi, asp, exe, com, bat, pif... Security
display_cart_products_tax_rates N Taxes
display_productcode_in_list N Appearance
display_shipping_cost Y Appearance
display_taxed_order_totals N Taxes
dont_leave_https Y Security
download_key_ttl 24 Egoods
dynamic_save_money_enabled Y Product_Options
egoods_manual_cc_processing N Egoods
email_addresses Logging
eml_af_sk_expire Y Anti_Fraud
eml_af_sk_invalid Y Anti_Fraud
eml_giftcert_notif_admin Y Gift_Certificates
eml_giftcert_notif_purchaser Y Gift_Certificates
eml_login_error Y Email_Note
eml_lowlimit_warning Y Email_Note
eml_lowlimit_warning_provider Y Email_Note
eml_newsletter_subscribe Y News_Management
eml_newsletter_subscribe_admin Y News_Management
eml_newsletter_unsubscr Y News_Management
eml_newsletter_unsubscr_admin Y News_Management
eml_order_c_notif_customer Y Email_Note
eml_order_d_notif_customer Y Email_Note
eml_order_p_notif_admin Y Email_Note
eml_order_p_notif_customer Y Email_Note
name value category
eml_order_p_notif_provider Y Email_Note
eml_profile_deleted Y Email_Note
eml_profile_deleted_admin Y Email_Note
eml_profile_modified_admin Y Email_Note
eml_profile_modified_customer Y Email_Note
eml_recurring_notification Y Subscriptions
eml_signin_notif Y Email_Note
eml_signin_notif_admin Y Email_Note
enabled_printable_version Y Appearance
enablePostMailGC Y Gift_Certificates
enable_all_shippings N Shipping
enable_debug_console N General
enable_init_order_notif N Email_Note
enable_init_order_notif_customer N Email_Note
enable_manual_cc_cvv2 Y General
enable_order_notif Y Email_Note
enable_shop_statistics Y Advanced_Statistics
enable_tracking_statistics N Advanced_Statistics
enable_user_tax_exemption N Taxes
export_invitems Y QuickBooks
extra_fields_limit 10 Extra_Fields
featured_only_multicolumn N Appearance
FEDEX_account_number Shipping
FEDEX_integration_type
FEDEX_meter_number
FEDEX_test_server Y Shipping
fields_status User_Profiles
froogle_currency USD Froogle
froogle_expiration_date 1 Froogle
froogle_password Froogle
froogle_payment_accepted Froogle
froogle_payment_notes Froogle
froogle_used_https_links N Froogle
froogle_username Froogle
gcheckout_check_avs Y Google_Checkout
gcheckout_check_cvn M Google_Checkout
gcheckout_check_prot Y Google_Checkout
gcheckout_default_shipping_cost 0.00 Google_Checkout
gcheckout_disable_customer_notif Y Google_Checkout
gcheckout_display_product_note N Google_Checkout
gcheckout_merchant_calc Y Google_Checkout
gcheckout_mid Google_Checkout
gcheckout_mkey Google_Checkout
gcheckout_test_mode Y Google_Checkout
gc_blocking_period 120 Gift_Certificates
gc_show_expired Y Gift_Certificates
gpg_home_dir Security
gpg_key Security
gpg_prog /usr/local/bin/gpg Security
gpg_public_key Security
html_catalog_dirs
html_mail Y Email
httpsmod libcurl General
https_proxy General