What does Available Size mean in Order Presets in TWS?

From both Mosaic and Classic TWS you will need to access Global Configuration and select Presets in order to create, edit, or remove presets for your orders. 

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To create presets for your orders, in both Mosaic and Classic TWS you will want to access Global Configuration and select Presets. 

You can configure profit-taker and stop-loss order presets in the areas labeled "Target Order (Profit-taker)" and "Attached Stop Order", respectively…

When configuring Hotkeys in TWS, some drop-down menus allow you to choose "Default". For example, you can set your order size to be "Default", "Absolute" or "Available". If you select "Default", TWS will use the values defined in your Order Presets…

This message "Display size is not supported for OTCBB stocks" indicates that the Iceberg order type is not supported for US Penny Stocks.

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