What does APP_BLE_CONN_CFG_TAG do?

I have searched through the examples and the documentation (BTW the online document links are broken - the offline documentation is nice however).

  • From what I can tell, this is a flag, always set to '1'.
  • The comments all read like this:

/**< A tag for BLE stack configuration */

  • It eventually gets pass into


/// @param[in] conn_cfg_tag  The connection to configure

  • When passed into to the advertising configuration:

ble_advertising_conn_cfg_tag_set(..., uint8_t ble_cfg_tag);

/// @param[in] ble_cfg_tag Configuration for the connection settings (see @ref ble_cfg_tag)

From what I infer, this value is associated with a BLE connection that can/may be established.

Specific questions:

  • If I am setting up multiple connections, should each of these values should be unique?
  • The default value is single connection examples seems to be '1'. So it seems this is not a zero-based index. Can I use the value zero here?
  • Are the values arbitrary, within the uint8_t range? Are there any forbidden values? 0xFF for example?
  • Other than being unique, I'm guessing this is a key for my usage by which I can keep track of a connection. Is this a correct interpretation?