USE of forever begin end. If it is a complex always BLOCK statement like always (@ posedge clk or negedge reset_)

always @(posedge clk or negedge reset_) begin

if(!reset_) begin
data <= '0;
end else begin
data <= data_next;
end
end

// Using forever : slightly complex but doable

forever begin
FORK
begin : reset_logic
@ (negedge reset_);
data <= '0;
end : reset_logic
begin : clk_logic
@ (posedge clk);
if(!reset_) data <= '0;
else data <= data_next;
end : clk_logic
join_any
disable fork
end

Use of forever begin end. If it is a complex always block statement like always (@ posedge clk or negedge reset_)

always @(posedge clk or negedge reset_) begin

if(!reset_) begin
data <= '0;
end else begin
data <= data_next;
end
end

// Using forever : slightly complex but doable

forever begin
fork
begin : reset_logic
@ (negedge reset_);
data <= '0;
end : reset_logic
begin : clk_logic
@ (posedge clk);
if(!reset_) data <= '0;
else data <= data_next;
end : clk_logic
join_any
disable fork
end