---
title: IDs and 64-bit precision
summary: UniverseID, UI handles, NPCSeed and the exact-integer limit of Lua numbers.
section: ui
kind: guide
status: observed
tags: ["X4","modding","ids","and","precision"]
sources: ["https://wiki.egosoft.com/X4%20Foundations%20Wiki/Modding%20Support/"]
---
## ID representations


UI handles, script component IDs and UniverseID cdata have different contracts. Establish what one call returns and the next expects. In X4 9.00 research, applying `ConvertIDTo64Bit` to an already numeric ID returned nil. A precautionary universal conversion is not a substitute for checking types.



## Exact integer range


A double-based Lua number cannot represent every integer above `2^53`. This matters for NPCSeed and other 64-bit values. The example demonstrates LuaJIT representation, not a game call. Define a canonical storage type and encoding; do not pass exact values through `tonumber` when the range can exceed double precision. `tostring(cdata)` may contain a type suffix.




```lua
local ffi = require("ffi")
-- Синтаксис 64-битного литерала LuaJIT.
local exact = ffi.new("uint64_t", 9007199254740993ULL)
local text = tostring(exact)
-- У tostring(cdata) может быть суффикс типа.
```

## Reference lifetime


Do not store a temporary UI handle as a permanent ship reference across loads. Resolve the object again in the current context and check existence. A name or macro is not a unique instance identifier.



## Verification


Round-trip a large seed through your real read/storage path. Include invalid and missing objects, reopening the menu and save loading. Compare original and restored values without intermediate rounding.