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diff --git a/include/util/types.h b/include/util/types.h
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+/*
+ * include/util/types.h
+ *
+ * Copyright (C) 2023 Douglas Rumbaugh <drumbaugh@psu.edu>
+ *
+ * All rights reserved. Published under the Modified BSD License.
+ *
+ * A centralized header file for various datatypes used throughout the
+ * code base. There are a few very specific types, such as header formats,
+ * that are defined within the header files that make direct use of them,
+ * but all generally usable, simple types are defined here.
+ *
+ */
+#pragma once
+
+#include <cstdlib>
+#include <cstdint>
+#include <cstddef>
+#include <string>
+
+#include "util/base.h"
+
+namespace de {
+
+using std::byte;
+
+// Represents a page offset within a specific file (physical or virtual)
+typedef uint32_t PageNum;
+
+// Byte offset within a page. Also used for lengths of records, etc.,
+// within the codebase. size_t isn't necessary, as the maximum offset
+// is only parm::PAGE_SIZE 
+typedef uint16_t PageOffset;
+
+// A unique identifier for a frame within a buffer or cache.
+typedef int32_t FrameId;
+
+// A unique timestamp for use in MVCC concurrency control. Currently stored in
+// record headers, but not used by anything.
+typedef uint32_t Timestamp;
+const Timestamp TIMESTAMP_MIN = 0;
+const Timestamp TIMESTAMP_MAX = UINT32_MAX;
+
+// Invalid values for various IDs. Used throughout the code base to indicate
+// uninitialized values and error conditions.
+const PageNum INVALID_PNUM = 0;
+const FrameId INVALID_Fshid = -1;
+
+// An ID for a given shard within the index. The level_idx is the index
+// in the memory_levels and disk_levels vectors corresponding to the
+// shard, and the shard_idx is the index with the level (always 0 in the
+// case of leveling). Note that the two vectors of levels are treated
+// as a contiguous index space.
+struct ShardID {
+    ssize_t level_idx;
+    ssize_t shard_idx;
+
+    friend bool operator==(const ShardID &shid1, const ShardID &shid2) {
+        return shid1.level_idx == shid2.level_idx && shid1.shard_idx == shid2.shard_idx;
+    }
+};
+
+const ShardID INVALID_SHID = {-1, -1};
+
+struct SampleRange {
+    ShardID run_id;
+    size_t low;
+    size_t high;
+};
+
+}